Adds initial typescript support

BREAKING CHANGE: Renovate is now distributed as a "built" package on npmjs, using `dist/` instead of `lib/`. For nearly everyone, it should still just work though.

Closes #3644 again!

fix(config-validator): fix cache init with no directory

feat: unify file locations

Closes #545 

Extend renovate-config-validator to validate `config.js` and `RENOVATE_CONFIG_FILE`. Also add the execute bit to `config-validator.js`

Fixed #3388

I haven’t used Heroku with Renovate in over a year and am not able to directly support it. I think it would be best to be made into a “wrapper” repository like https://github.com/renovatebot/renovate-heroku

BREAKING CHANGE: renovate repository no longer supports direct deployment to Heroku

Renovate will now put all its data in `path.join(os.tmpdir(), '/renovate’);` and will instruct npm and yarn to do the same. To force Renovate to use a specific folder, set `process.env.TMPDIR` when running. The previous variable `RENOVATE_TMPDIR` is now deprecated and will be rewritten to TMPDIR.

Closes #1794

packageRules selectors should only ever be inside a packageRule object, or at the top level of a preset. This feature enforces this rule with a validation check.

Closes #1773 

Closes #1734

Fixes #1632

Adds “renovate-config-validator” as a new bin entry to package.json. Can be run without arguments and will check renovate.json, .renovaterc, .renovaterc.json and package.json. Returns non-zero exit code with a description if there are errors.

Instead refer to website and source code.

Use `cacache` to persist changelog results between runs.

This commit drops support for nodejs 6 now that nodejs 8 has reached LTS. Renovate will now publish only the `lib/` directory and not `dist/`. Some babel is necessary to leave in-place because Jest otherwise crashes when encountering the spread operator.

BREAKING CHANGE: Node.js 6 is no longer supported

Renovate will now depend on yarn like any other dependency and call this version directly, instead of having an embedded version. This will allow us to "renovate" the yarn version we use too.

Renovate now uses an embedded yarn binary. This way, the version of yarn used can be known + there is no requirement for Renovate admins to install yarn separately.