made settings more testable
client testability
added TestClient base impl, added xUnit and Fluent Assertions
made changes to facilitate tests, laying pipe for fixture impl
added test fixtures from Recurly php client, added FixtureImporter and tests
Merge branch 'testfixtures' into v2_2014_dev

Conflicts:
	Test/Recurly.Test.csproj
updated extensions with XML comments, added EnumNameToTransportConvention extension for functionality of turning .NET enum naming to the kind expected by the API, added tests
removed unnecessary TODO
fixed write usages of enums, added test for enum transformations
redid paging in RecurlyList, modified Client to sent link urls, added extension to return named urls from link header (and tests around that), added paging to AccountList. partial commit, sln is uncompilable at the moment.
completed paging implementation on remaining lists