Added RAM_total + test to snmp.AirOS backend
Added RAM_free + test to snmp.AirOS backend
Changed structure in to_dict method RAM_free addition
Improvements to snmp.AirOS backend
 * little cleanup in firmware
interfaces_number in snmp.AirOS backend + test related to #5 and #19
Sintactic sugar fixed (too much)
Added another oid in ssid property in smnp.AirOS backend
Merge branch 'master' of https://github.com/nemesisdesign/netengine