Upgrade from optparse to argparse:
1. 'type' field now needs to be callable (deleted if type was 'string' as that is the default)
2. 'extend' action re-implemented for argparse
3. 'callback' action no longer exists, re-implemented as a custom argparse action (only used in buildbase.py)
4. minor api changes, e.g 'add_option' -> 'add_argument'
MozReview-Commit-ID: HcKowF13Da3
--HG--
extra : rebase_source : e5e8160d91263fb273f790dbda5e2c2b2e02eaf6