Changed str->unicode in common/djangoapps/utils/.

LMS-2436
Some more str->unicode fixes in instructor and courseware apps.

LMS-2429
Support emitting analytical events from xblocks running in the LMS

XBlocks can and should use the "publish" method provided by the runtime to emit analytical events. In theory we could now start replacing calls to track_function with calls to publish, however, that migration is not handled by this change.

Fixes: AN-789
Reduce false cache misses when evaluating prerequisites
Merge pull request #3097 from edx/dcs/paver-reqs

Reduce false cache misses when evaluating prerequisites
temporarily remove SR on capa alerts to fix problem submissions (LMS-2474)
Merge pull request #3058 from edx/usman/lms2429-unicode-error-fixes

Unicode support fixes
fix raw grade dump in standard instructor dashboard
Added test and cleaned up code formatting
Review based changes
Converting class method and attributes to private
Remove unused methods from comment_client
Remove unused *args and **kwargs from perform_request
Use requests library utility method for getting json results
Add more tags to comment_client request metrics

This captures real-time metrics for all of the comment client actions,
segregated by course_id, as well as other small-cardinality fields.

The goal is to be able to detect changes in forum usage, with the goal
of alerting on potential error conditions.
Merge pull request #2613 from edx/bugfix/ichuang/idash-raw-grades-dump

fix raw grade dump in standard instructor dashboard
Merge pull request #3105 from edx/adam/hotifx-js

temporarily remove SR on capa alerts to fix problem submissions (LMS-247...
Merge pull request #3089 from mulby/gabe/publish

Support emitting analytical events from xblocks running in the LMS
this will allow for clientside javascript reporting
Merge pull request #3109 from edx/jarv/upgrade-newrelic-agent

this will allow for clientside javascript reporting
Add datadog metrics logging for django model creates, updates, and deletes
Skip video test that is failing in master
Merge pull request #3111 from edx/zoldak/skip-failing-tests

Skip video test that is failing in master