Let the Loader's basedir be the packages_dir, fix module reloading.

This is required, at least on Linux, where CWD is in fact /opt/sublime_text,
which prevents from correctly loading modules.  Also, python3 replaced reload by
imp.reload.
Specify an empty string for regions icon, otherwise Sublime complains.
Python3' sort now requires a 'key' keyword argument.

key must be a function that extracts the comparing keys for each element.
Ran 2to3 on the capp_lint module
Updated pyflakes to version 0.6.1, which is python3 compliant
Use set_timeout_async to load modules, otherwise packages_path is undefined.

One could think about using a plugin_loaded method, but this interferes with
plugins initialization, as described in:
http://www.sublimetext.com/forum/viewtopic.php?f=2&p=43063

Jon's advice seems to be using set_timeout_async, so this is what's done here.