1. add debug opts like log-level for local env. 2. move no-colors opt as...

... settings variable
Suggest the ability to add casper logs with colors for local env.
under settings file:
# Casper JS log level. any of `info`, `debug`, 'warning`, `error`
CASPERJS_LOG_LEVEL = 'debug'

# Other casperjs non test case specific options.
# set the no-colors option for example jenkins (production environment)
CASPERJS_NON_TEST_SPECIFIC_OPTIONS = {'no-colors': ''}