add and edit challenge
fix edit challenge
transactional and push edit only if number or name changed
fix some coding convention issues
fixing some typos
indentation and handle for challenge with no exercises
for challenges that dont have any pdf
for challenges that don't have any pdf shouldnt set any value while submitting
fix indentation
fix more of indentation
fixes for adding challenges with no course/exercise
Merge pull request #241 from anubhavsinha/add-edit-challenge

add and edit challenge