Course Create now respects default course format

Course Create command had a hard-coded default of 'weeks', which meant
that default configured in Admin->Courses->Course Default
Settings->Format was not respected.

Removed the hard-coded default, and updated the command to use the
value of the setting variable moodlecourse | format when the -F flag is
not specified.
Merge pull request #58 from bbusschots-nuim/140710_fixCourseCreateDefaultFormat

Course Create now respects default course format