Fix field AssessmentPart.criterion to point to Criterion table.

Migration 0020 incorrectly altered the field to point to the
CriterionOption table.

TNL-826
fixed the multi-line issue for criterion prompt, criterion option text,
peer assessment feedback and self assessment feedback.

TNL-814
Merge pull request #634 from edx/usman/tnl826-assessment-part-criterion-foreign-key

Fix field AssessmentPart.criterion to point to Criterion table.
Code refactoring after PR code review.

TNL-814
Merging master into this branch
Code refactoring after PR code review.

TNL-814
Minor code refactoring.

TNL-814
Merge pull request #636 from edx/muzaffar/tnl814-multiline-issue-ux

fixed the multi-line issue for criterion prompt, criterion option text,
Imported and configured bi-app sass module for rtl support.

TNL-813
Replaced direction related css properties with mixins from bi-app-sass.

TNL-813
Added single-box-shadow sass mixin with rtl support.

TNL-813
Flip fontawesome's icon-caret-right 180deg in rtl.

TNL-813
Upgraded sass framework neat to v1.7.0.

TNL-813
Added bidi versions of neat mixins: span-columns and omega.

TNL-813
Sass fixes for rtl.

TNL-813
Merge pull request #639 from edx/usman/tnl813-rtl

Sass changes for RTL.
Update i18n strings.
Updated translations from Transifex.
Merge pull request #645 from edx/usman/translations-2014-12-12

Translation strings update.
Fixed grades issue for progress page graph.
TNL-1022