Remove unnecessary xcode-select check

This is handled here:
https://github.com/Homebrew/homebrew/blob/67fbb313da8843234c4d1785c9c074af5a025394/Library/brew.rb#L34-46
Remove another unnecessary check
Don't call xcrun twice
Remove yet another xcode-select check
Xcode.bad_xcode_select_path? is used only once, so inline it
Fix syntax error
python: fix site-packages symlink

If the target exists and is a symlink to a directory, FileUtils.ln_sf
will follow the link and create the new symlink inside the target.

This results in a broken symlink like:
  /usr/local/lib/python2.7/site-packages/site-packages -> ../../../../../../../../../lib/python2.7/site-packages

Fix this by unlinking the target first.
Fix e97bbeb9a76578c46fa190884c1601b2713cddb0 for source installs
python: write distutils.cfg atomically
quassel 0.10.0

This release brings a new protocol with compression and snore
notification backend. For a full changelog see;

https://github.com/quassel/quassel/blob/0.10/ChangeLog
quassel: add 0.10.0 bottle.