fix search button in firefox
generic classes for search boxes
use % instead of em for font size
pep8
Only show proposals in instance overview if proposals are enabled
Omit possible excessive <hr> use in instance overview

If multiple instance overview content elements are defined installation
wide, but do not exist in an instance, a `<hr>` had been painted anyway,
erroneously.
Merge pull request #694 from xi/feature-firfeox-search-button

fix search button in firefox
Merge pull request #687 from xi/feature-tile

create tile interface component
create instance option display_category_pages
allow long badge descriptions
add category image

Conflicts:
	src/adhocracy/config/routing.py
	src/adhocracy/controllers/category.py
add config ui for category image

Conflicts:
	src/adhocracy/controllers/badge.py
allow to set proposal category in query on new
add parameter extra_filter to solr_proposal_pager
add parameter visible_only to model.badge.all
add category tab to instance navigation
create category views
only show leaves in category index
use pages_pager in category sidebar