Allow hyper::method::Method to be put in HashMap

This is needed for porting iron/router to hyper.
Add some basic tests for hyper::method::Method

This test case does not attempt to test all the methods exhaustively,
but it does at least test all the methods in the APIs.  There's also a
check to make sure that Method can be used as part of a hash-table key.
Merge pull request #144 from emk/method-eq

Allow hyper::method::Method to be put in HashMap