This change replaces the cliff-tablib json formatter with an internal
replacement. It differs from the tablib formatter in the following ways:
- by default outputs with an indent of 2 spaces. The --noindent formatting
argument outputs with no indentation, to save space or to pipe to tools
which can't handle multi-line input.
- emit_one serialises a simple dict where the column name is the key
and the data item is the value (rather than a list of dicts with
'Field' and 'Value' keys)
The cliff release which contains this change will need a corresponding
cliff-tablib release which removes the json formatter from its setup.py
entry_points.
Change-Id: I7f9b1f339d96ead347a0c9d95ec7004a78d8c9d5
Related-Bug: #1308744
4e1470d93e