Created new service ProjectsService and removed methods in repos_projects that belong to ProjectsService.
Minor tweaks by @gmlewis following review.
Fixes#461.
Closes#467.
Change-Id: I8b85ff6e716151b505c843c905534bd5fe8257ae
Note that this is an API-breaking change but should have minimal
impact on users of this package due to the nice inference
properties of the Go programming language.
Bumped `libraryVersion` to `2` due to API-breaking change as
discussed in #376.
Fixes#180.
Change-Id: Ib386135e6b8f306d1f54278968c576f3ceccc4e7