Encoding not set in HTTP Header when viewing raw files or commits (BB-3501)

Content encoding isn't specified in HTTP headers when viewing "raw" commits or "raw" files. As a result text often renders incorrectly. Screenshots are attached and here are some links to some affected documents https://bitbucket.org/winstonw/lolwut/raw/5e4250c864e4/README and https://bitbucket.org/winstonw/lolwut/changeset/5e4250c864e4/raw/.

The links should render correctly if your web browser falls back on UTF-8. I found this issue present in Opera 11.61, lynx, and Chromium 17.