resolves height issue when display the check and show answer actions alongside problems
removes HTML elemements from problem action Sass selectors
abstracts height rule to apply to the capa check, show, save actions
syncs styling rules for buttons/inputs to ensure consistency
syncs up font-weight across problem button/input actions
Merge pull request #136 from edx/fix/btalbot/xmodule-showanswer

Problem Show Answer/Check Button Line Height Syncing