Add some clarity to the I2CS device is not linked error message, teling us WHICH device.
Merge pull request #217 from krkeegan/insteon_linking

Insteon: Change "initiate linking as controller" Group to 00
Merge pull request #244 from krkeegan/user_code_fix

Do Not Move Tabbed 'Add' Entries in User Code to Global Declaration
Merge pull request #256 from pmatis/Insteon_Clarity

Insteon clarity
Merge pull request #259 from krkeegan/Zero_State

Allow for State of 0
Insteon: Add Success_Callback to Message Object

Success_callback is eval'd when the ACK for the message is received.
- Note: There are so many callbacks all over the place within the code, it might be nice to condense as many as possible into this routine.
Insteon: Add routine for Linking I2CS devices

The routine requires a few steps to complete
Insteon: Add Callback to Routines used by Link to I2CS

Each routine needs to have success and failure callback parameters
Insteon: Convert Link_to_Interface to Handle i2cs or non-i2cs devices

The routine first checks to see if the device will respond to a get_engine_version request.
If any ACK is received the routine continues as normal.  In this case even if the device is an I2CS, the device must already have link entries as it responds to the PLM.
If a NAK is received, it is assumes that this device is an i2cs and the link_to_interface_i2cs routine is called.
Merge branch 'insteon_i2cs_linking' into running
Merge branch 'running' into running_hopcount