First steps to get devappserver2

This was hacked together using the test devappserver2 package that google released a few weeks back.  It works by attempting to load the original dev_appserver and then falling back on devappserver2 if dev_appserver isn't available.

However, on the 1.7.5 SDK release, both dev_appserver and devappserver2 are provided side by side, so this code won't actually kick in.  I'm working on adding a command line parameter to select between the two.