update bok choy db caches
update export_all_courses management command to count and list all failed export courses
removing rake and  outdated references to it
TinyMCE Plugin: Added media plugin to TinyMCE for the Annotation tool

- fixed missing media and link buttons on image

 - fixed a CSS issue with the sharing button
Merge pull request #4250 from edx/zub/story/listallexportfaildcourses

update export_all_courses management command to count and list all faile...
Request IFRAME API every time with https scheme.
Merge pull request #4717 from edx/alex/fix_test

Request IFRAME API every time with https scheme.
Merge pull request #4634 from edx/clytwynec/removing_remaining_rake_references

removing rake and  outdated references to it
Merge pull request #4687 from lduarte1991/lduarte-harvardx-pr16

TinyMCE Plugin: Added media plugin to TinyMCE for the Annotation tool
Annotation Tools: Added Grouping Plug-In

- adding comments

 - spacing issues and indentation
Merge pull request #4504 from lduarte1991/lduarte-harvardx-pr11

Annotation Tools: Added Grouping Plug-In
update bok choy db caches
Merge branch 'mvo/update_bok_choy_db_caches' of https://github.com/edx/edx-platform into mvo/update_bok_choy_db_caches
Merge pull request #4636 from edx/mvo/update_bok_choy_db_caches

update bok choy db caches