Shift responsibility of updating and creating points to decoder

[maharjanaman]

Changes:

• Decoder function only returns an error (if any)
• Logic to update points is moved to decoder functions
• If the decoder doesn't find the point in the device while performing the update, it creates a point and then performs an update (shifting responsibility to auto-create points to the decoder)
• Remove the operation to create points automatically when a device is added

Resolves #28