Fix faraday 0.9.0+ breaking gemignore add
Version bump to 0.4.1
Trap Sigint so that Ctrl+C triggers "at_exit"
Force UTF-8 when writing to cache

If we receive UTF-8 but Ruby assumes ASCII-8bit, writing the
cache to a file fails because of invalid byte sequences. Thus
we assume that we've received UTF-8 from GitHub.
Replace ObjectSpace finalizer with "at_exit" (less hack-ish)
Version bump to 0.5.0