Add media keys support

Adds SPMediaKeyTap git submodule
Merge pull request #3 from leolobato/master

Add media keys support on 10.5+
Added Leo Lobato to Credits.rtf
Added a CHANGELOG entry about global media keys
Bumped year in NSHumanReadableCopyright
Bumped CFBundleVersion
Added README.markdown entry for SPMediaKeyTap
Updated experimental build URL
Enabled NSSupportsSuddenTermination