It seems like self.tabs is getting set to an empty set [] now rather than None. This causes the tab defaulting to not populate, leading to crashes in the LMS if someone makes a new course with additional tabs (e.g. static tabs or pdf-textbooks)
add new test to assert that course creation will populate default tabs as expected. Also update factory to not override defaults on tabs array. Also simplfy self.tab test condition.
Merge pull request #481 from edx/fix/cdodge/regression-on-tabs-initialization

It seems like self.tabs is getting set to an empty set [] now rather tha...