Fix paver python prereq paths
Add ADDL_INSTALLED_APPS to studio for parity with lms
Remove package_id and remove lower_ stuff from migrator
STUD-1603
i18n: Make values that has 'display_name' be displayed localized in editor

Dictionary values like Boolean, or some other value types which has 'display_name' can now be displayed with the localized version.
Added trailing slashes otherwise the course_id regex sometimes eats up get parameters.

LMS-2738
Get rid of skiptests
Split mongo correctly serializes and deserialized references
STUD-1592, STUD-1603, LMS-2642
Add tests for has_course
and negative tests for get_course.
Merge pull request #3745 from edx/dhm/no-package-id

Dhm/no package
Merge pull request #3899 from edx/opaque-keys

Opaque keys
BLD-725: ChoiceGroup i18n.
Fixed change log table format & pdf errors
Merge pull request #3875 from louyihua/translation-fix

i18n: Make values that has 'display_name' be displayed localized in editor
Merge pull request #3903 from edx/ahodges/documentation/data_chg_log

Fixed change log table format & pdf errors
Merge pull request #3487 from edx/ammar/fix-paver-python-prereq-paths

Fix paver python prereq paths
Extract opaque_keys into a separate library

[LMS-2571]
Fix exception on Internet Explorer when adding first transcript language

Internet Explorer throws an "Invalid argument" exception when uses an empty string as the parameter in ```namedItem``` method.
Change empty string into null value can maintain browser consistency.
Do not persist anonymous ids when exporting for all students of a course.

For large courses this causes export to take a long time and to time out.

LMS-2747
Merge pull request #3901 from edx/dhm/opaque-dont-skip

Dhm/opaque dont skip
Merge pull request #3900 from edx/dhm/test_has_course

Add tests for has_course