When a field has choices, display the verbose version.

Fixes the second point of #8.
Fixes line length.
Tests against Django 1.6 and the latest minor versions of 1.4 & 1.5.
[Travis CI] Removes Django 1.4.10+Python 3 from the matrix.
Merge pull request #12 from BertrandBordage/master

When a field has choices, display the verbose version.