Lines cleaner

This code analysis checks if there are trailing spaces
and tabs (anywhere).

This is not only what flake8 does already, as this is done
for not only python files but also any other kind of files.

Trailing spaces and tabs (anywhere) are *always* evil.
Prefer single quotes over double quotes
Check for old style python string formatting
Add a code analysis tool for checking imports

According to plone.api style guide import should be done
one per line:
http://ploneapi.readthedocs.org/en/1.0.0-rc.1/contribute/conventions.html

This code analysis tool is a basic validator for that.