Merge pull request #12 from jwhitlock/1095584_postgres_tests

fix bug 1095584 - PostgreSQL fixes
Merge pull request #14 from jwhitlock/1093106_feature_relations

Fix 1093106 and 1093120 - Fixes for browse app of test data
Merge pull request #15 from jwhitlock/1093122_django_17

fix 1093122 - Convert to Django 1.7, migrations
bug 1098672 - add and populate Feature.mdn_uri
bug 1098672 - Switch feature.mdn_path to .mdn_uri
bug 1098672 - Drop feature.mdn_path from database
bug 1098672 - Update loader for Feature.mdn_uri
bug 1098672 - Update browse app for mdn_uri
fix bug 1098672 - Update documentation