Disabled transients for logged in users.
Fixed naming of dates, cities, permalinks, summary filters in WPT_Production.
Closes #53.
Moved filters to separate WPT_Filter class.
Added a new 'date' filter. Closes #50.
Added magic dates to event listings:
`[wpt_events day="today"]` and `[wpt_events day="tomorrow"]`.
Closes #54.
Make sure permalink structure is consistent when running query tests.
Closes #48.
Improved syncing of categories between productions and events.
Closes #25.
Re-enabled travis tests for multisite because #48 is fixed.