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
Merge pull request #16 from jwhitlock/1098672_mdn_uri

Fix 1098672 - Convert feature.mdn_path to mdn_uri