Updates middleware register call to work with Faraday 0.9.

Keeping support for Faraday 0.8 as well, and tweaking existing hash syntax to hash-rockets so this gem works with MRI 1.8 too.
Merge pull request #3 from pat/latest-faraday

Updates middleware register call to work with Faraday 0.9.
Reorg for more semantic layout
Merge branch 'master' of github.com:bhaberer/faraday-digestauth
v0.1.0