Remove --verbose from pyqi driver

Fixes #164
Driver is more robust to errors

If a config can't be loaded, it is reported separately from the rest of the successfully-loaded commands. This allows users to see a list of all available commands even if there's an issue with their installation.

Fixes #165
Driver distinguishes between bad import and non-existing command
make_optparse now fills in bool flags correctly

Fixes #153
Remove unnecessary imports from make_command

Fixes #150
Merge pull request #166 from jrrideout/death-march

Usability improvements for driver