Merge tag 'hotfix-2014-05-02' of github.com:edx/edx-platform into edx-west/rc-20140508

Merge releases up throught Hotfix on May 02, 2014

Conflicts:
	common/djangoapps/student/models.py
	common/djangoapps/student/views.py
	common/lib/capa/capa/capa_problem.py
	common/lib/capa/capa/customrender.py
	common/lib/capa/capa/responsetypes.py
	common/lib/capa/capa/tests/test_answer_pool.py
	common/lib/capa/capa/tests/test_shuffle.py
	common/lib/capa/capa/tests/test_targeted_feedback.py
	common/lib/xmodule/xmodule/capa_base.py
	common/lib/xmodule/xmodule/tabs.py
	common/lib/xmodule/xmodule/tests/test_delay_between_attempts.py
	docs/en_us/developers/source/xblocks.rst
	lms/djangoapps/certificates/views.py
	lms/djangoapps/courseware/views.py
	lms/envs/common.py
	lms/templates/courseware/course_about.html
	lms/templates/courseware/course_navigation.html
	lms/templates/instructor/instructor_dashboard_2/metrics.html
	lms/templates/problem.html
	lms/templates/register.html
	requirements/edx/github.txt