Addressing code review comments
Merging exception creation with throw
Merge pull request #127 from AzureAD/servicing

Adding tracing via TraceSource and adding TraceSwitch for controlling the level of tracing using System.Diagnostics.Trace
Update README.md
Update README.md
Update README.md
Update README.md
Update README.md
Increasing assembly version to 2.13
Updating branch names for the pull requests

**Bug fixes for the current stable version need to go to 'servicing' branch.**
**New features for the next version should go to 'dev' branch.**
Update contributing.md