Re-enable bug-reference-github following upstream merge
Only use ido-ubiquitous in Emacs 24, which it now requires
Don't use ido-ubiquitous-disable-in, which has been removed upstream

Fixes #127
Clarify installation instructions (see #129)
Require new separate magit-svn package
Better handle maximize-frame when frames are full-screen
Merge remote-tracking branch 'purcell/master'