(Not Really Needed) Importer bug fix.

When we were using Scrapy (web spider), we encounterd some issues with
it failing to load some super nested code.

This supposedly fixes it.  It is unlikely that this patch is actually
needed in production currently.
Fix idea project resource patterns.

For a project that has a number of various resource files, this will now
generate:

"?*.json;?*.creds"

Rather than

?*{'.creds?': True, '.json': True}

Which Intellij (12) cannot interpret.
Remove site-packages from sys.path for pex files.

Pants makes a (somewhat feeble) attempt to scrub site-packages out of
the
sys.path in an attempt to have an 'hermetic' system.
This fails pretty badly on some of our osx installation, and this simple
hack improves its accuracy.