fixes #1598 fixes #1599 use xml to assoc video->exam
tool to merge a group of problem set reports to end up w one row per student
put the username in quotes
Merge pull request #1663 from Stanford-Online/jinpa-master-survey-merge-tool

tool to merge a group of problem set reports to end up w one row per stu...
Merge pull request #1661 from Stanford-Online/jbau-xml-video

fixes #1598 fixes #1599 use xml to assoc video->exam
Merge pull request #1660 from Stanford-Online/dca_new_working

Assessment student data report (#1594).
Assessment Summary report which replaces Problem set summary report
(#1595)

As it turns out, this was quite simple as it is a report of a single
assessment with same format as the Combined Summary Assessments
report.

Also, includes some final cleanup of the old problem set reports that
are no longer required.
Merge branch 'master' of http://github.com/Stanford-Online/class2go into dca_new_working