Add some Reports API endpoints.
Don't try to parse the text output from Reports.GetReport.

Instead, just stick it in a 'BinaryResponse' object.
Added basic support for submitting feeds.
Added feeds getter.
Support fetching feed checking.

Amazon don't have a response envelope for this but use amazon envelope so had to
cater for that.
Fixed inventory_supply_list being nil bug.
Make sure we exclude options so :body isn't sent via GET too.
Correctly handle amazon envelope results.
Upgrading httparty version.
Merge branch 'master' of github.com:RichGuk/ruby-mws
add get report test
merge in basic feeds from RichGuk
merge branch from radicaled and fix conflicts
fix test for downloading file