#2029 - New relation examscore -> examrecordscore

**Note: Migration required for this change.

I'm setting this new relation in 2 instances:

1. Autograded responses. For this the examrecordscore related to is the
one corresponding to the score with penalties excluded.

2. CSV grading. For this, the examrecordscore related to is the one
which is for the latest submission (attempt) at the time of csv upload.
This is because csv grading, as currently works, posts grades to the
last submission for that exam. In this instance, the score on the
examrecirdscore is the same as the examscore as there are no
machine penalties applied with csv grading.

What I have not touched is the regrader. The reason being, that I'm only
setting relations for new submissions, not retroactively. It ought to be
easier to incorporate after current courses have died.
The case where csv grades are being set for a student who has not
attempted this exam yet needs to be handled.
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
#2298 Added "Username" as column title for Student Scores in-line
report
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
#2290 - changed text to label for TOS checkbox
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
Someone stole my migration placeholder.
some changes to left nav to be more accessible
Merge branch 'master' of https://github.com/Stanford-Online/class2go into giulio-tpg-report-2290
made announcement expand/collapse UI much more user friendly
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2
add hidden descriptor to dropdown menus to inform keyboard navigators of dropdownn status
enabled tab selection on left nav headings but added link following prevention
added accessible features to left nav
reordered html order of arrow/save/submit buttons for accessible logic
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working2