refactor: repositoryUrl -> sourceUrl

lib/datasource/github.js

lib/datasource/npm.js

lib/datasource/nuget.js

lib/datasource/packagist.js

lib/datasource/pypi.js

lib/datasource/readme.md

lib/datasource/terraform.js

lib/manager/npm/extract/index.js

lib/manager/travis/package.js

lib/workers/pr/changelog/index.js

lib/workers/pr/changelog/source-github.js

lib/workers/pr/index.js

lib/workers/pr/pr-body.js

lib/workers/repository/onboarding/pr/pr-list.js

lib/workers/repository/process/lookup/index.js

test/datasource/__snapshots__/github.spec.js.snap

test/datasource/__snapshots__/npm.spec.js.snap

test/datasource/__snapshots__/nuget.spec.js.snap

test/datasource/__snapshots__/packagist.spec.js.snap

test/datasource/__snapshots__/pypi.spec.js.snap