Fix spelling of 'equivalent'

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Move function comments into docstrings, fix spelling

Signed-off-by: Dan Mick <dan.mick@inktank.com>
provision.py: require cobbler_url to be set

Log an error and return False from reimage_if_wrong_os() if
cobbler_url isn't set in the configuration

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Fix line lengths

Signed-off-by: Dan Mick <dan.mick@inktank.com>