Added Consultation type filtering

Modified the publication_filter_option to take an optional group_key which will be used to group the options into an optgroup, also allowed overriding the slug value so that 'All consultations' slug is not changed.

Tidied up some dead code (consultation_type_filter_options) and whitespace.

Added in the new filter options and reordered the ids, the closed consultation also includes outcome.

https://www.pivotaltracker.com/story/show/40495565