Added Profile78 v4.5 portable class library

- SystemClock.cs changed to Task.Delay via IFDEFs on PORTABLE
- BrokenCircuitException on PORTABLE is not Serializable.
changed namespace and assemblyname to Polly

Was "Polly.PCL" now "Polly" which is the existing convention.
corrected Thread.Sleep replacement

https://stackoverflow.com/questions/12641223/thread-sleep-replacement-in-net-for-windows-store
https://github.com/michael-wolfenden/Polly/pull/4#issuecomment-37346084
Merge pull request #4 from ghuntley/pcl

Added Profile78 v4.5 portable class library
Sleep should be reset to the same action it was initialized with
Reference the Net45 library for unit tests
Update version and information to include PCL addition
Update nuget.exe to v2.8
Enable xml documentation for PCL library
Modify build to include PCL library in NuGet package
Update NuGet description to include PCL addition
Make Polly unsigned by default and migrate signed to Polly-Signed. Closes #5.
Fixed minor typo.
Merge pull request #7 from grumpydev/patch-1

Fixed minor typo