Renamed activity_days to activity_since

Doesn't seem to be used anywhere, so shouldn't break
anything. Except maybe Eduskunta Explorer!?
Member activity API refactoring and enhancements
Fix bug in previous commit
Front page: Implement party list with JS over the API
Make DB connections persistent
Use daily average activity in party listing
Add search support to API using Haystack
Calculate keyword activity in DB
Merge remote-tracking branch 'jami/master'
Add pysolr to requirements
New activity scores

Attempts to make "mean" average daily activity over year
10, ends up in 6.1
Fixed and refactored kamu-grid.css

Hopefully doesn't break every layout
Refactored MP listing stuff to single implementation
Added spinner to party member list
Add last_modified_time to social.Update
Add translated keywords
Enable Solr indexing
Add automatically generated translations for keywords
Help dialogs for graphs and tagclouds
Revert "Add translated keywords"

This reverts commit 9b002571eb8ce6cf1ac43fc867da40cba80fe517.