Styling nit: proper order for the import
Fix ambiguity errors in `.extra()` call

Fixes #7.
Cleanup: removed unused stylesheets
Cleanup: removed dead stuff
Cleanup: removed django admin
Cleanup: unified admin URLs
Unified names for named URL patterns
Docs: Add URL patterns and extend template naming on styleguide
Cleanup: removed dead code
Drop support for Python 2.5

The Travis configuration exclude matrix is kept for further reference.
Nit: removed extra whitespace