Removed unused placeholders
Pass arguments through
Add interactive prompt for user/pass

Fixes #7
Merge remote-tracking branch 'upstream/pr/15'

Conflicts:
	scripts/pepper
Change libpepper local() function to match LocalClient().cmd()

A function signature like this may be nice for people scripting
against one or both APIs.
Pass targeting options through

Closes #6.
Remove empty default value for -a flag
Remove hard-coded valid eauth backends

We can't easily guess possible valid values here since new backend
modules can be easily added outside from the modules that ship with the
core Salt distribution. That said, if the user doesn't provide a value
here optparse will just grab anything the comes next, even another valid
flag (is that right?) so it would be nice to have some kind of
validation here...