fix: allow rebaseStalePrs=false to take priority over repo settings

Upgrade ranges to latest version even if latest version satisfies existing range.

| name    | value   |
| ------- | ------- |
| type    | boolean |
| default | false   |

By default, Renovate assumes that if you are using ranges then it's because you want them to be wide/open. As such, Renovate won't deliberately "narrow" the range by increasing the semver value inside.

For example, if your `package.json` specifies a value for `left-pad` of `^1.0.0` and the latest version on npmjs is `1.2.0`, then Renovate won't change anything. If instead you'd prefer to be updated to `^1.2.0` in cases like this, then set `upgradeInRange` to `true` in your Renovate config.

This feature supports simple caret (`^`) and tilde (`~`) ranges only, like `^1.0.0` and `~1.0.0`. It is not compatible with `pinVersions=true`.

Closes #1607

Remove outdated packageFiles description

Adds initial support for `.nvmrc` renovation. If the existing value is a fully-specified semver version then it will be upgraded, otherwise left alone.

Closes #1270 

Retains the "node" configuration object but moves enabling/disabling to "travis". Also removes the default `supportPolicy` from config.

A semver range defining allowed versions for dependencies

| name | value  |
| ---- | ------ |
| type | string |

Use this - usually within a packageRule - to limit how far to upgrade a dependency. For example, if you wish to upgrade to angular v1.5 but not to `angular` v1.6 or higher, you could defined this to be `<= 1.5` or `< 1.6.0`:

```
  "packageRules": [{
    "packageNames": ["angular"],
    "allowedVersions": "<=1.5"
  }]
```

* chore: update dependency prettier to v1.11.0

* update prettier results

Adds support for upgrading `node` version in `package.json` > `engines` if the current version is pinned.
- Does not convert from range to pin
- Ignores ranges
- Does not upgrade major versions

Assuming `sharebe` -> `shareable`

Adds a new feature to limit the number of concurrent branches/PRs to have open at any one time. Defaults to 0 (disabled), set it to a positive integer to enforce that limit.

Adds a `renovate/verify` status check for those migrating and looking for familiarity. Better to check the GPG verified commit, as mentioned in the associated doc.

Adds new config option `versionStrategy` that allows config to override Renovate’s autodetection of when to “widen” an existing semver range, and when to “replace”.

Closes #1351

This reverts commit 58716ff3.

Adds a new configuration option that allows you to bump the version number in the package.json being updated. e.g. you might configure Renovate to bump a patch every time, or maybe for dependencies only and not devDependencies. e.g. if you configure `"bumpVersion": "patch"` then a Renovate PR updating a `package.json` that used to be version `1.2.1` will now see it updated to `1.2.2` (in addition to the dependency version(s) being updated too). Thanks to @gunar for the feature suggestion.

Closes #861

Closes #1396, adds reference to comments by @LinusU

This PR adds the capability to renovate more than one base branch at a time. For instance, a project may have their released `3.x` version on `master`, while an upcoming `4.x` is being prepared using branch `next`. `4.x` might have a quite different set of dependencies (e.g. some removed or some added) so it's not appropriate to only target `master` and keep rebasing, as it will get messy. Instead, it's necessary to target both `master` and `next` to keep both updated.

Closes #1279

Adds a feature to enforce an hourly limit on PR creations.

Closes #1363

Adds new configuration option “pathRules”. pathRules is an array of path rules. Each rule should contain a “paths” array which uses string or glob matching like the existing ignorePaths. If any of the paths in a rule matches a packageFile then the remaining configuration from the rule is applied to the packageFile.

This PR adds new checks that:
- Website configuration options are listed in alphabetical order
- Every relevant configuration option in source code is documented on the website
Website docs have been updated accordingly to pass.

Closes #543, Closes #1310

Closes #1311