add CanSkip attribute to quizblock
store score in user attempt to prevent recalculation
datamigration for initial score
Update css in flag input
Merge branch 'labster/master' of github.com:Bodekaer/Labster.EdX into labster/master
add problems field in UserAttempt to store all problems scored. 
data migration to fill problems field
Merge branch 'labster/master' of github.com:bodekaer/Labster.EdX into labster/master