Add ability to map new name for the fields and headers

Currently Debezium extracts the exact fields from inside the message and places them as fields/headers
(via the configuration parameters "add.fields" and "add.headers") .

It would be great if we can give the option of new name while doing so.

For example, 

"add.fields" => "field1[:newName1],field2[:newName2],field3[:newName3]"
"add.headers" => "field1[:newName1],field2[:newName2],field3[:newName3]"

 As the "new name" is optional we aren't disturbing the people who already use this feature.