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
A request handler for get and post and the rest
Fix tests, delete unused request handlers
Fix a test failure
It is not repeatable to modify the request headers in place
One integration test failed with "An item with the same key has already been added" due to this
Merge pull request #128 from AnthonySteele/uni_requesthandler

Uni requesthandler
Remove the RequestHandlerFactory
as we don't need multiple RequestHandler classes now
RequestHandlder.HandlesMethod is also removed as it always returned true
RequestCoordinator is next as requests now just pass straight through it
remove line added in error
Merge pull request #129 from AnthonySteele/RemoveRequestHandlerFactory

Remove the RequestHandlerFactory
Flattened base class into AllRequestHandler as it was the only subclass
Route params logic from base class is now in RouteParamsSubstitutor
Rename "AllRequestHandler" to just "RequestHandler"
Also GetRequestHandlerTests and PostRequestHandlerTests now both test this class
so they are RequestHandlerGetTests and RequestHandlerPostTests
added an interface to RequestHandler
Merge pull request #130 from AnthonySteele/SimplerRequestHandler

Simpler request handler
Put tests around RouteParamsSubstitutor
Tests on RequestCoordinator can be on RequestHandler instead
Deleted the Request coordinator class.
RequestHandler steps into its place
Merge pull request #131 from AnthonySteele/RemoveRequestCoordinator

Remove request coordinator
RouteParamsSubstitutor as a non-static class with dependencies via the constructor
to keep it the same as everything else. It's not injected into RequestHandler .. yet
Merge pull request #132 from AnthonySteele/InstanceRouteParamsSubstitutor

RouteParamsSubstitutor as a non-static class
Add HttpPut and Httpdelete attributes
and code to handle them when they are applied to endpoint dtos
All the attributes target classes, i.e. [AttributeUsage(AttributeTargets.Class)]