Convert to XCTestCase.
Change to use module instead of #import.
Modernize the syntax.
Remove Xcode 6 warning.
Add basic handling for HTTP GET requets.
Change to queue HTTP GET requests.

This prevents the same request from being sent to the server more than
once while the first request is already pending.
Add GET and POST support.
Add option to cache an existing file.

This copies the file to the cache storage area.
Add download file support.
Add image download methods.