Refactor to IHttpClient
towards supporting all the http verbs
One method on IHttpClient per request verb is a constraint that we need to remove
Merge branch 'master' into http_methods

Conflicts:
	src/SevenDigital.Api.Wrapper.Unit.Tests/EndpointResolution/RequestHandlers/GetRequestHandlerTests.cs
	src/SevenDigital.Api.Wrapper.Unit.Tests/EndpointResolution/RequestHandlers/PostRequestHandlerTests.cs
	src/SevenDigital.Api.Wrapper/EndpointResolution/RequestHandlers/PostRequestHandler.cs
Merge pull request #127 from AnthonySteele/http_methods

One method on IHttpClient for get, post etc