Miscellaneous changes

See merge request brian/mymusiclist!14

Fix navbar issue and add w3.css styling

See merge request brian/mymusiclist!13

Implements album art auto retrieval with caching

See merge request brian/mymusiclist!12

Add unique email constraint for User

See merge request brian/mymusiclist!11

> Changes Ed Sheeran's album named multiply from × to x, which fixed album art finding
  for this title.

> to use, download 'pip' which is python's package manager, then run pip install musicbrainzngs.
> tested using python2.7

Refactor the whole codebase

See merge request brian/mymusiclist!10

Adds search features, album views, artists views, and increases dummy data size

See merge request brian/mymusiclist!9