PEP8: cleanup
My simple pep8 cleaner
PEP8: W293 blank line contains whitespace
PEP8: W602 deprecated form of raising exception
PEP8:  E301 expected 1 blank line, found 0

Improve readability
Add help text
PEP8: E225 missing whitespace around operator
PEP8: E227 missing whitespace around bitwise or shift operator
PEP8: E231 missing whitespace after ','
PEP8: E271 multiple spaces after keyword
PEP8: cleanup
Bump up depcheck for tookit version
Provide proper previous_view_url for non-root deployments.

SCRIPT_NAME wasn't being taken into account so django.urlresolvers.resolve
could return unexpected matches.

Fixes bug 2767.
Upgrade Select2 to the latest available version.

Includes some nice bugfixes worth incorporating before the actual 3.4
release happens.