Fix a bug of "run-button not functional when there were any errors."
refine code
remove extra blanks
change grading.save to grading.update_column
the save function is in the save callback previously.
add comments of the usage of exp_crate_or_changed in update_exp_transaction
Merge pull request #210 from wangqiang1208/bugfixing/level-achievement-display-twice

Fix level/ achievement display twice bug
fix contest survey summary view
Merge pull request #208 from wangqiang1208/bugfixing/code-run-button

Fix a bug of "run-button not responding when there were any errors."
Merge pull request #211 from wangqiang1208/bugfixing/survey-summary

fix contest survey summary view
Merge branch 'development' of github.com:Coursemology/coursemology.org into Deploy