Merge pull request #211 from adamarla/master

Storing user/app signature
Sharpened logic for enabling/disabling stab menu states ...

In particular, Show Answer should be enabled (has answer) even if Check Answer cannot be
(insufficient codices)
Merge branch 'master' of github.com:abhinavc/web-application
codex and answer flags, also recording ans_check for school assignments
reworded a statement
made price deducted same as that listed on app