Use ConfigArgParse

[manics]

omego uses argparse classes directly, so will fail with the changes in ome/yaclifw#7

This PR makes ConfigArgParser mandatory, and also disables all support for environment variables.

• See Simplify the command line options in omego #27 (comment)

Testing

You should be able to specify config values in an ini file (or yaml if PyYAML is installed). All config values should be at the top level (they are not split between subcommands, [section headings] are ignored). If specified the -c/--config file.ini argument must come before the subcommand.

E.g.

$ cat << EOF > config.ini 
branch=OMERO-DEV-latest
verbose=True
EOF

$ omego -c config.ini download py --skipunzip

is equivalent to

$ omego download py --skipunzip -v --branch OMERO-DEV-latest

Todo

• Bump yaclifw version in requirements.txt and setup.py

[sbesson]

Closing as this conflicts with several files and will need some work.