Move test_units.ini under assets folder.
Add example XBRL files for testing purposes.
Change back to PyQt4.

Drop PySide and move back to PyQt4.
Add new UTR measures to units.ini.
Detect case sensitive measures dynamically.

Update the add_namespace function so that it is able to dynamically
detect which measures have a matching measure with an opposite
capitalization, such as utr:mm and utr:MM, instead of relying on a
hardcoded list.
Update test_get_units to utilize a setUp function.
Add test for xbrl.add_namespace function.
Add .editorconfig.
Make indentation in setup.py four spaces.
Remove duplicate tests for acre measure.
Add test for xbrl.extended_measures function.
Merge create-tests branch.