Added NUnit 2.6.3 test runner.

nunit-console added async/await in version 2.6.3. Added the
runners nuget so that this version can be used to
execute the tests correctly.
Resolved NuGet issue with Chatter toolkit
Additional updates to functional tests for Chatter client
Merge branch 'master' of github.com:developerforce/Force.com-SDK-for-NET
Uncommenting Force.com CI tests