Allow users to see course materials by section from dropdown #858

Extends get_course_materials function to return materials for single
section. Meant for viewing live sections, thus why there is no dropdown
for instructor's edit view.
interactive autograder: log on call, more exceptions (#1729)

Also fixed an unqualified exception.
gather associated text: trim whitepace and odd chars (#1729)
Refactor left_nav.html for improved readability

* Partial rewrite of get_full_contentsection_list for improved
  concision, readability, and to change the shape of full_index_list:
 * Instead of a sorted list of lists of tuples, it is a dictionary of
   sorted lists of dictionaries. This allows for nicer lookups in
   left_nav.html with less iteration overall.
* Update to left_nav.html to take advantage of this change. Also
  introductes local variable value caching using {% with %}
* Introduction of byKey template filter, which allows lookup into a
  dictionary by tha value of a template variable, rather than by its
  name: i.e., 'somedictionary|byKey:variable' will return
  somedictionary[variable] rather than somedictionary['variable']
* Correction of {% url %} reverse for exams in left_nav.html
  (fixes #1630)
File format change from DOS to Unix
Connection in own function; granular exceptions handling (#1729)
Chris exercise conversion script (#1729)

Squirreling away here for good measure.
Merge branch 'master' of github.com:Stanford-Online/class2go into sef-1729-interactive-exercises
Merge pull request #1742 from Stanford-Online/dca_new_working2

#1740 Mark db records as "csv imported"
Label the page and form differently depending on the action being taken
Fix for #1714

Separate fix on different branch for repetition fix and new iconage

	modified:   templates/exams/view_exam.html
Merge pull request #1736 from Stanford-Online/jrbl-1630-exams-reverse-wrong

Jrbl 1630 exams reverse wrong
Refinements to child exam appearance

* Child exams are indented a little bit more and their titles are
  rendered a little bit smaller, to make groups of child exams more
  easily visually distinguishable from their parent.
  (fixes #1699)
Merge pull request #1744 from Stanford-Online/wescott-master-1714-fix

Fix for #1714
Merge pull request #1743 from Stanford-Online/jinpa-master-1741

Label the page and form differently depending on the action being taken
Merge pull request #1739 from Stanford-Online/sef-1729-interactive-exercises

Small interactive exercise fixes for sprint 28 (#1729)
Merge pull request #1747 from Stanford-Online/jrbl-1699-distinguishing-child-exams

Refinements to child exam appearance
Merge pull request #1697 from Stanford-Online/kluo-858-materials-by-section

Allow users to see course materials by section from dropdown #858
Fixes #1765; csv grade export messed up

Re-written to conform to new tables.