Fix issue #1295: Added a check to see if every group being collected had only one TA assigned to them.
Fix for issue 1295: DIsabled button if more than one TA is marking the same set of submissions.
Added check to second branch to make sure it fails for any user except for a TA.
Fix warnings generated by assert_select

Some tags are not closed properly, so the HTML parser complains when
doing assert_select in functional tests.

Tested:
- rake test:functionals
Rename rubocop-todo.yml to .hound.yml
Tweak Hound for method chaining

Prefer having a leading dots when chaining method invocations.
Merged Master fixed conflict.
Added translations for French and Portuguese, also did some formatting.
Fix for issue 1485. Updated controller to include values 500 and 1000 so that it will be added to the show xx per page filter.
Merge pull request #1499 from gello88/issue-1485

Fix for #1485. Updated controller to include values 500 and 1000.
Merge pull request #1428 from ealonas/issue-1295

Fix issue #1295: Check to see if every group being collected had only one TA assigned to them.
Merge pull request #1483 from zhangsu/fix_assert_select_warnings

Fix warnings generated by assert_select.
Merge pull request #1481 from zhangsu/hound_ci_config

Tweak Hound for method chaining
Improve performance of grader-group assignment

Grader assignment to groupings are currently done in nested loops, so
each grader/group combination will issue a query to the database, which
is slow. This can be solved by doing a bulk operation in single queries.

The view also requires some fields that are not eagerly loaded in the
controller, which introduces n+1 query problems.

This patch improves the back end performance of assigning, randomly
assigning and unassigning graders, as well as populating the grader
index page. Assigning graders to criteria is still slow. The front end
is also super slow (it takes a few seconds just to check all the
checkboxes when the number of groups is over 1000!).

This partially solves #1443. The front end JavaScript also has to be
GREATLY optimized to fully resolve that issue.

Tested:
- rake test:units
- rake test:functionals
- local server testing
  - with
    - 2 assignments
    - 3 TAs
    - 1000+ students and groups
    - 2 * 3 * 1000+ = 6000+ TaMembership records
  - wall clock response latency is < 5 second for the optimized
    operations (only counting the back end, the front end can take more
    time than the back end to load)
Fix tests affected by modified parameter format

The query paramters for unassigning graders are changed from
<grouping_id>_<grader_username> to <grouping_id>_<grader_id>, so some
test cases need to be updated.
Add tests for Assignment#criterion_class
Add tests for update_assigned_groups_counts
Add tests for new class methods of Grouping