Remove references to /tmp in tests

Including:

* Change path for mongo_metadata_inheritance to use unique temp dir
* Update SASS_CACHE_PATH with thread-safe temp dir
* Remove hard coded directory reference for grades download tests
* Remove hard coded directory reference for direct mongo test
Merge pull request #5566 from Kelketek/lazy_coursemode_translation

Lazy loading of CourseMode model's internationalization.
Merge pull request #5589 from edx/christina/tnl-399-remove-save

Do not save an xblock after rendering the Studio view.
Open source rename child-id
Merge pull request #5597 from edx/benp/doc-paver-changes

Doc for paver quality switches.
Merge pull request #5562 from mlkwaqas/waqas/tnl526-search-magnify-glass-not-working

Clicking the magnifying glass should perform search
Merge pull request #5609 from edx/zoldak/remove-tmp-references

Remove references to /tmp in tests
Fix sychronization issues in LTI test
Better verification for troubleshooting LTI test failures
Dismiss any lingering alerts after lettuce scenarios
Platform API doc
Clarify Max Attempts

Add text to clarify relationship between Max Attempts setting
course-wide vs individual problems
Merge pull request #5607 from edx/carol/docs/DOC-1054

Clarify Max Attempts
Update the student transfer command to transfer to multiple courses.

Quick cleanup

Making kwarg to suppress unenroll events.

pylint and pep8 errors cleaned up.

add commit on success.

Changing transactional behavior of the management command.
Add remember me checkbox to the login page
Merge pull request #5608 from edx/zoldak/lti-test-fixes

Fix sychronization issues in LTI lettuce test
Merge pull request #5621 from edx/will/remember-me

Add remember me checkbox to the login page
Use password field type for the login form password
Merge pull request #5619 from edx/sanchez/transfer-student-command

Update the student transfer command to transfer to multiple courses.
Initial pass at LMS and Studio RTL
LMS RTL fixes
switching RTL on the fly - added bi-app for sass compiling