used helper constant REPORT_COLUMNS
Changes to eliminate requirement for 'new' report in session

Significant changes to add_participant so to not require report in session.
Participant count now computered via js selection/count of relevant participant
elements. Further, all state regarding added participants now resides only
in DOM and does not touch db until save/submit.  As a result, remove_participantno longer generates request to server; all work done locally.

Significant changes to partials that required report object, specifically
those involved with rendering 'reason' and 'common reason' checklists. Removed
dependence on report; now the reason checklist require only an array
of 'reason (infraction) ids.

Reworked javascript to affect changes to common reasons, eliminating trip
to server.

NB: Still work to be done with a) create+add participant and b) new_with_participants.

NB: Support for contact details is NOT up to date
Merge branch 'rails-31' of github.com:rkgordon3/radar into rails-31