Loosen restrictions on hashie gem.
Use callback in Mashify middleware.
Update gemspec for Faraday 0.9.0
Fix Proxy test for all current Faraday versions
Fix Mashify test to work with Faraday callback
Only patch Multipart-Post if neccessary, don't hardcode content-type
Merge branch 'dan/hashie' into dan/master
Merge branch 'dan/faraday-0.9' into dan/master