Allow Application model customisations with a new config value

Also changes the original Application model to allow the search index
configuration to be altered (otherwise the first one wins)
Basic search configuration
Corrected search engine setup, with placeholders for future model fields
Merge branch 'issues/25-search-engine-setup' into hampshire
Add a select2 search box to the homepage
Load maps js on map page only
Don't allow VCR to re-record test interactions
Give fields slightly better names and titles to match wireframes