Maintenance updates

* Upgraded mail-base to Ubuntu 14.04 LTS
* Updated branch names for rainloop which were changed upstream
Make a shallow clone of rainloop
Use generic ubuntu archive url and update saucy -> trusty
Update mailpile dependencies
Update Dockerfile to new mailpile syntax
Fix broken rainloop install

* Copy necessary rainloop files to /var/www/html
* Updated README
Fix example formatting
Add explicit (MIT) license
Add owncloud container
Add owncloud instructions to README
Fix typo in README