Fixed hasStyle() on non object error in tests
[VersionManagement] Created extractor for version number
[VersionManagement] Used the VersionExtractor in Application

The application now takes the VersionExtractor as a dependency, tests
have been updated and use the `version_file.md` fixture so it will never
change (version set to '2.1.0' for tests).

Now the only file that need to be changed is on a new release is
`VERSION.md`
[VersionManagement] Added update of the version
Merge branch 'feature/version-management' into develop