Update to Reel 0.4

There are two failing adapter lint tests, most likely due to bugs in Reel's
Content-Length calculation.
switch to enumerable request.body
hetetepe 0.5.2 uses http-parser.rb 0.6.0.beta.2
Bundle Reel from RubyGems instead of git
Merge pull request #116 from seancribbs/reel-0-4-support

Update to Reel 0.4