Make storm starttime more reliable

Storm "starttime" is currently based on data that has been loaded. Before automatically saving if a threshold is crossed (if that ends up being needed), the process_fire method should check if additional data needs to be loaded for a station to accurately report when the storm started. Relates to #50 (closed)

The following discussion from !44 (merged) should be addressed:

• @jmfee started a discussion: (+4 comments)

  Is save related to the threshold being crossed?

  Slightly unrelated, is there a reason the threshold summary is buffered instead of printing during the loop?

/cc @frengers