Rewrite release json updater
Transform serialized releases into the format that phpbrew will support.
Update release list
Improve pre-built release list json
Add FetchReleaseListTask
Add getPHPReleaseListPath method to Config
Use FetchReleaseListTask to fetch release list in known command
Change remote release list filename
Add KnownCommandTest
Add version key
Fix json_decode
Suspicion: phar tests produce class redeclare issue.
Remove processUncoveredFilesFromWhitelist from phpunit since it breaks testing on travis ci
Adjust release list methods
Add ReleaseListTest
Refactor list fetching code to ReleaseList
Refactor current install command to use new ReleaseList class.
Remove use of PhpSource

Summary:

- Disable known unstable command since release manager site does not
work anymore

- Use new ReleaseList

- Add getReadyInstance method to get a release list ready ReleaseList
  object.
Update package.xml file