Implementation of #67 - Add Support for R,W, etc as Either<uint, string>

* Added string extension method for ToRpbOption to return a uint from a string
* Created internal Dictionary for QuorumOptionsLookup
* Updated quorum asserts to include "default"
* Changed R, W, etc in RiakDeleteOptions, RiakPutOptions, RiakGetOptions
* Modified RiakClient to use new SetXYZ methods
Updated ToRpbOption to use assert to check for all, quorum, one, default during RpbOptionification.
Added notes about Issues fixed by this code
Merge branch 'feature/EitherRW' of github.com:DistributedNonsense/CorrugatedIron into develop

Conflicts:
	CorrugatedIron/Extensions/StringExtensions.cs
	CorrugatedIron/RiakClient.cs
	CorrugatedIron/Util/RiakConstants.cs

Fixed up line-ending issues (I hope!)