Add info about template for Checkbox problem type

Change text to "click Checkboxes on the Common Problem Types tab" and
add image of checkbox button
Correct minor formatting error
Add JSInput template information

Update Advanced Problems page with Custom JavaScript Display and
Grading (JS Input) problem info. Delete separate page for JS Input
problems. Update Appendix F with new code for sample JS Input problem.
Update JS Input to reflect new template in Studio

Update Advanced Problems file and Appendix F
Hide staticpages preview on render
STUD-1071
Add & to contents to verify that import/export still works.

Part of STUD-91
Add acceptance test for behavior when & is in problem xml.

Part of STUD-91
a11y: manage focus appropriately for modals with iframes in IE (LMS-1539)
update rewriteStaticLinks utility function(modifiy only relative urls)
STUD-674
fix tinymce popup size too small
STUD-674
add validation for grading types (allow only integers)
STUD-988
The function tzAbbr() causes null-reference exception when the browse returns a non-English timezone string.
Add 'Yihua Lou <supermouselyh@hotmail.com>' to the AUTHORS file.
Very Minor tweaks to the LMS and CMS startup.

I was going to do something in the startup code, then changed my mind,
but didn't want to just discard these changes.
Add options to dump_course_structure to output inherited metadata.
Add tests for inherited metadata to test_dump_course, and move to commands/tests dir.
prevent failure when module does not have a data field
Studio: adds in developer-centric Sass file
* provides new .scss file for developers to add temporary/in-progress Sass for further refactor/polish
* cleans up note/import order in shame and application Sass files
LMS: adds in developer-centric Sass file
* provides new .scss file for developers to add temporary/in-progress Sass for further refactor/polish
* cleans up note/import order in all application scss files
Miscellaneous fixes to strings found during i18n work.