Milestone CMU Lab:S2.g RSpecs as basis for CMUlab-emulator coordination

Move to an RSpec based model for wireless channels in the emulator.

Status: "We have defined the XML communications used to configure the wireless channels in our testbed: ​http://moo.cmcl.cs.cmu.edu/wiki/index.php/Wireless_Emulator/schemas This more broadly fits into the general Rspec/Emulator docs found here: ​http://moo.cmcl.cs.cmu.edu/wiki/index.php/Wireless_Emulator_Rspec"