In the event of a pylint failure, we need to cat the log. This will also
ensure that the remaining scripts in the job can run.

The jenkins-common script is the better place for this particular setup, since that
script is doing similar setup steps to prepare the environment for running
various tests/subsequent scripts. This also will resolve downstream processes,
such as our jenkins AMI builder (for jenkins-worker images).

Note that because js testing occurs on a different CI job than python
unit testing, files will not be clobbered by this change. The python unit
testing job also creates the same-named report through the diff_coverage
task.

The platform includes jshint as a development tool, and our
builds are enforcing a limit on total number of jshint violations.
This commit will enforce no new jshint violations on a per-change
basis, much like pylint and pep8 are enforced. So with this change,
we'll be enforcing our linting requirements consistently, regardless
of type of violations.

Also on Jenkins, runs quality task after installing jshint.

This complexity metric is created by using radon (see changed files for additional
documentation links). This tool calculates cyclomatic complexity and provides a numeric grade
where a lower number is better (e.g., less complex).

JShint will be executed with paver run_jshint, which will use a defined set of
directories (likewise defined are directories to ignore). A limit can be imposed
on the total number of violations. Note that this change does NOT include adding
jshint to diff-quality or `paver run_quality`.

This reverts commit 52c4aaca.

With the old logic, we weren't running pylint on openedx at all.  We
were also running it on lms/lib/comment_client twice, and on the
installed xblock third-party library.

will fall in 'shard 6'

We are not using the limit flag in the actual run_pep8 method; removing
that from scripts. Operationally, pep8 has been enforcing a limit of
zero for awhile; this finishes that realization.

Also, all pep8 reports now appear under the reports/pep8 folder, rather than
per-system.