* Save data for 24 hours in the rfmonitor directory. The files are now
  gzipped, we use pako JS library to gunzip them at the client browser.

* Save data that corresponds to violations, in the archive directory for
  7 days.

* Change the violation email to reference the frequency graph for the
  current data set.

* Lots of changes to the frequency graph code to handle specific log
  files (by unix timestamp) and build a menu of all of the available
  data files so the use can flip through the data sets.