Prevent PhantomJS auto install

* Upgrade jasmine to 2.0.2
* Use new config.prevent_phantom_js_auto_install option to avoid
security errors
Merge pull request #289 from alphagov/stop-phantomjs-download

Prevent PhantomJS auto install
Move existing specs for View models

* were in a flat structure, needed to correspond to hits/mappings
Add a View::Mappings::Filter

* A starting point for getting too many fields out of MappingsController
* Encapsulates filtering and sorting, takes params and produces a
  mappings collection
Replace all the filter fields in the view

* Where they were, for example @incompatible_filter, change to
  @filter.incompatible?
* Tests mostly broken
Fix the tests

* Where @filter could be nil, use #try
* Unrecognised filter-by-types shouldn't count to Filter#active?
* Sorting by hits should count to Filter#active?
Move trailing slash to canonical_filter

* This was in the controller
* It didn't need to be, this is a job for the filter
Move much of filter_helper to View::Mappings::Filter
Minor cleanups

* Didn't need a field for mappings
* consistency with local variable names in tag add/remove
Inline Filter#by_tag? and #by_tags?

* Use the collection methods #any? and #include? instead