Unwinding the usage of HiveQueryToMysqlTask in enrollment

Removing HiveQueryToMysqlTask from the codebase and adding in controls for overwrite_hive and overwrite_mysql

Fix HiveQueryToMysqlTask dependency in student_engagement workflow

Introduce pip-compile tooling

The order import query now retrieves the UUID of the course (not to be confused with course run) for which an entitlement was purchased.

LEARNER-1745

Fix source for course_subjects in BigQuery load.

Remove traceback info.

Updated analyze script to support newer releases of EMR.

pycodestyle reads from setup.cfg so there is no need for an additional file.

LEARNER-1745

- All imports have been sorted using isort
- Unused imports have been removed
- isort is now run as part of code quality checks

LEARNER-1745

A Dockerfile is now included so that developers can use a Docker image/container for local testing. Travis now builds the Docker image and runs tests on the container. The image is pushed to Docker Hub for successful master builds.

LEARNER-1745

LEARNER-1745

Incrementalization of user-activity.

Update pep8 to pycodestyle.

Move course-subjects to use the discovery API

Pin some google-related packages.

Handle null-duration video events.

Handle failures in _finish for Vertica.

Update boto version.

Add host argument to s3_connect.  Update unit test patches to match.
Host argument is now required by boto.  Latest version of boto provides a
hook to read from a .boto file, and there is a way for remote-task
to set such a file up and then read from it.  However, it's not
clear how to get the .boto file to the task instances in a multi-instance
cluster so that the file would be read by boto when reducers open
their own streams to output to an S3 file.

Like an earlier fix already applied to MySQL.

use video duration from events

EDUCATOR-1411

Added parameter import_credentials to HistogramFromSqoopToMySQLWorkflowBase

Allow empty inserts for ModuleEngagementSummaryMetricRangesMysqlTask

for sites with periods of low activity.

Inspect traceback for handling end of output error.

Add missing backslash for null ascii.