Remove the redundant namespace from app names

[damonkelley]

Currently the name of the apps are prefixed with coda_

• coda_mdstore
• coda_replication
• coda_validate
• coda_oai

Considering how the coda project to used be structured in subversion, this namespace made sense because the apps did not live inside the repository for the larger project.

Since the apps now live inside the coda project in version control, and because the project name is coda, it is a good idea to remove the coda_ namespace. Leaving us with

• mdstore
• replication
• validate
• oai

Not only will this look a bit cleaner when viewing the directory, but it will also clean up the imports.

[damonkelley]

Removing this from the Upgrade to Django 1.8 milestone because this will alter the database schema. We should hold off on this until we are able to more easily make database changes on deploy.