pass in headers to restclient
remove dupe line
add a regression spec around Connection#request

Previously, it was throwing away headers when setting up RestClient::Resource.
This spec ensures that won't happen again.

This is assuming that passing the headers to RestClient::Resource then does the right thing, but that seems a fair assumption to make.
spec the right thing

i.e. we're claiming to spec the request method, so let's call that directly
Merge pull request #59 from blake-education/master

Pass in headers to restclient