Updated the gem to work with the new heroku platform-api gem

Most of this is custom stuff for my ITs On Me application.  Not sure if you would find it useful.
However, the code for using the new heroku platform-api gem is in there.  The heroku-api gem is deprecated.
Fixed a bug where redis['last_scaled'] was nil on my platform 

Also, this gem now spins up to a max and down to a min that can be set in the env vars.

There is some wacky code to decide when to add dyno and when not to , kinda weird , its very custom to our platform .. 

Thanks for your gem , hope this can contribute some ,  I plan on iterating on this a bit to optimize it and fix whatever bugs arise.

Jon