Merge pull request #126 from MITx/victor/progress-tracking

common/lib/capa/capa_problem.py

common/lib/xmodule/capa_module.py

common/lib/xmodule/progress.py

common/lib/xmodule/seq_module.py

common/lib/xmodule/tests.py

common/lib/xmodule/vertical_module.py

common/lib/xmodule/x_module.py

lms/djangoapps/courseware/grades.py

lms/djangoapps/courseware/module_render.py

lms/static/coffee/src/modules/problem.coffee

lms/static/coffee/src/modules/sequence.coffee