Fix paver python prereq paths
Remove some outdated code.
Updates to problem location for opaque keys
Remove package_id and remove lower_ stuff from migrator
STUD-1603
added and updated pavelib/quality.py from dglance branch, deprecated rake quality tasks
fix for pylint/pep8 defaults
Add the needed wait for ajax statements to checklist acceptance test methods
Opaque-keys: fix pep8 violations
Opaque-keys: fix pylint violations
Merge pull request #3843 from edx/zoldak/fix-brittle-checklist-acceptance-tests

Add the needed wait for ajax statements to checklist acceptance test methods
StaffFactories accept `course_key`s, not `course`s. Make that clear in the interface.
Fixed some TODOs, removed irrelevant ones
Merge pull request #3861 from edx/sarina/fix-quality

Fix quality violations from opaque-keys
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.
Refactor video volume control.
i18n: More extractable & localizable strings in xmodules
Merge pull request #3678 from edx/anton/refactor-volume-control

Video: refactor volume control.
Merge pull request #3878 from louyihua/master

i18n: More extractable & localizable strings in xmodules
i18n: Make XBlock buttons & components have localizable display names

1. Current code uses type name as the display names for XBlock buttons, so the name of these five buttons can't be localized. This fix contains code that adds a 'display_name' field for the buttons, and makes their names localizable.
2. The display names of components in advanced, html and problem types can be localized now.
i18n: Fix an i18n string extraction error in 02_html5_video.js

Replace a string concation to a single string to prevent the partial extraction of the string.