Fix the available? function

Now works as long as the version number is still /\d+\.\d+/.
Meta stuff updated.
Fix notifier downloads.
Merge branch 'ranmocy-master' into mavericks-fixes
Fixes and contributors preparing for release.
Fixes proposed in #15 for checking the OSX version by @railsme
Fixes after merging #8 by @jamilbk which broke the bin paths.
Bumped version number to 1.6.0