Battle Search now uses new search

The battle search page is the first of (hopefully all) of the pages to
be updated to use a new parameter system. The new system uses much more
user friendly form field names for the client, then converts them to a
ransack friendly parameters on the server side via a mapping system.

This has two advantages: firstly urls are now very user friendly and
don't have a mess of [] made url safe. Second, it provides inherent
filtering for queries as the query parameter is cleared before the
values are loaded into it (for security) and thus only the pre-defined
mapped parameters will be provided to ransack.