Add channel support to api.dartlang.org

This CL adds the following URL schemes:
  - http://api.dartlang.org/docs/channels/{be,dev,stable}/latest/
  - http://api.dartlang.org/docs/channels/{be,dev,stable}/424242/

Our channel builders are archiving the dartdocs to the following location:
gs://dartlang-api-docs/channels/{be,dev,stable}/REVISION/
Load all api documentation from the new channel locations

Changes include:
- Redirect old URLs to new channel documentation
- Update names for core libraries
- Update names for packages
Merge pull request #18 from mkustermann/channel-docs

Add channel support to api.dartlang.org
[ak] intermediate version
[ak] Latest version
Merge branch 'master' into dartdoc-next
force ssl for api docs
[ak] Works for bleeding edge
[ak] Pretty much working
[ak] Merged
[ak] Fix typos
[ak] Turn off forced SSL for the moment
[ak] Updated to client c12c3ae
[ak] Tidying
[ak] Don't worry about /latest
[ak] Turn on ssl. Means you need to connect via dartdoc-next-dot-dartlang-api.appspot.com
[ak] c87873e of dartdoc_viewer
[ak] version 212952c of viewer
[ak] b647386 of viewer