Insteon_Thermo: Convert i2 Entries to i2CS

Some of the older thermostat devices including the 2441v venstar device were i2 devices but do not support the newer thermostat code.

As such the distinction between the old and new devices is not i1 vs i2 but rather i2CS or not i2CS.
Insteon_Thermo: Check Engine Version of Root Device not ALDB Version

The ALDB can only be i1 or i2, need to be checking the engine version instead.