PISTON-1289: create_caller_id_name_if_undefined

[bradfordben]

Added new attribute to the users object 'create_caller_id_name_if_undefined' to allow the creation of the users caller id name to be optional when no caller id is defined.

Kazoo 5: https://github.com/2600hz/kazoo-core/pull/269 and https://github.com/2600hz/kazoo-crossbar/pull/190

[lazedo]

@bradfordben Hi, can't you do this on the client side before submitting ?

[bradfordben]

@lazedo Im not sure what you mean? Maybe im missing something?

So for an example where a kazoo device calls some endpoint B, Kazoo Device --- A leg ---> Kazoo/FS etc ---B leg---> Some endpoint B

Without the change if the kazoo device sets the caller id on the A leg it wont be used on the B leg as kazoo generates the default username if no caller id is set on the endpoint and uses that caller id name on the B leg.