changeDateFilter now dispatches only once. Closes #385

[jameshadfield]

please test before merge

using console.log statements, only 1 dispatch is being seen by the reducers, and only one lifecycle (ComponentDidUpdate, ComponentWillReceiveProps) of map is running:

SET INTERVAL START
reducers seeing  CHANGE_DATES_VISIBILITY_THICKNESS
map CWRP
map CDU
SET INTERVAL END (stack may not be clear)

Given the redux architecture and that animation uses the dispatch + react architecture to update things at each tick, I think this is the best we can do.