Ignore RavenDB 2.5 data directories.

Looks like the path has changed for this version of the database.
Update the Concerts' views.

Some of the classes hadn't been updated from Bootstrap v2 to v3, so that
fixes a lot of the immediate rendering issues.

There are some outstanding issues around the poster images, particularly
on the archive list pages.
Merge branch 'feature/update-concerts-pages-styling' into develop