mesh: Handle "options" dictionary in Send/Publish methods

mesh: Handle "options" dictionary in Send/Publish methods

This adds processing of "options" dictionary argument in Send,
DevKeySend & Publish methods on mesh.Node interface.

This new argument is a dictionary that currently has only one
new key word defined for Send() and DevKeySend():
    "ForceSegmented" - to force small payloads to be sent as
                       one-segment messages

In case of Publish(), and additional keyword is defined
     "Vendor" -  16-bit Company ID as defined by the Bluetooth SIG

Other key words may be defined in future to accommodate evolving
requirements of Mesh Profile specification.

Also, the addition of "options" dictionary to Publish allows to
eliminate VendorPublish() method (taken care by "Vendor" keyword).

Change-Id: I651165b5844fa2f709bcf563d17a07c8bbb0f324
Signed-off-by: anuj.bhumiya <anuj.bhumiya@samsung.com>