Added topic support, more bootstrap styles

### Implemented topic classification support:

* created MetaData_topics tables
* displaying topic labels for each item
* topics are clickable and searchable
* topic classifier function defined in local_settings.py
* home page filtering out 'Routine' legilsation

### Bootstrap and content updates

* using bootswatch journal theme (swapped out standard bootstrap.css)
* added proper viewport meta tags for responsive layout
* made search page consistent with others (offset1)
* correct markup for navbar-search
* changed bookmark label to star icon
* added shinier RSS image
* support for custom footer content in local_settings.py

### Files to ignore

* aldermen headshots
* SQL script for setting aldermen headshots (also, see https://github.com/open-city/councilmatic/issues/22)
* about.html