Update gopack dependencies.
Allow to parse relative url templates.

Otherwise Client.ResolveReference will override part of our urls when the endpoints contain path.
Make sure we resolve relative dependencies properly.
Make sure that hypermedia expanded links are composed properly.
Merge pull request #11 from calavera/relative_url_templates

Allow to parse relative url templates.
test and fmt everything
initial httpcache interface
implement a gob encoder/decoder for sawyer responses
make MediaType encodable
add mediatype/mediaheader decoding

cache the values manually so we don’t have to re-parse them
rename adapter => encoding
add a basic memory cache implementation
add Set()
push some code to EncodeTo and DecodeFrom
separate different hypermedia approaches
test mediaheader too
separate hypermedia approaches
roll mediaheader parsing into the hypermedia package.
fill sawyer.Response’s Rels on Decode()
typo
bring that TODO back