Moved from com.google.dart to com.github.sdb

Moved plugin names from com.google.dart to com.github.sdb

Also added a p2 repository builder, so we can test installing the feature in a vanilla copy of eclipse.

Sorry about the 400+ files changed; renaming a folder tends to have that effect.  If you have some changes you would like to merge before the rename, please send your commit hash so I can rebase before we merge this pull request.