templates: add support for filelog webcommand in json style
Modify changelistentry structure to also deliver phase and branch data and use
either 'parents' or 'allparents' depending on what is defined in the view, in
order to reuse it in filelog structure.
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.