Simplify bok choy environments to inherit pipeline settings from common.py
enable sharding of bok-choy tests
add shard_1 flags to cms bok-choy tests
use paver commands in jenkins script
updated doctring to explain the bok-choy shards
adding discussion tests to shard_1
Merge pull request #4593 from edx/clytwynec/shard_out_bokchoy_tests

Clytwynec/shard out bokchoy tests
Merge pull request #4597 from edx/benp/fix-bok-choy-solano

Simplify bok choy environments to inherit pipeline settings from common.
Fix false positive test in cms acceptance

This test was passing in Jenkins, but failing in our Solano runs (and locally on firefox).
This is because it was attaching a file that was not there. This change fixes the test
and makes the attachment method smarter so it will fail if it tries attaching a non-existent
file.
Add test file used for format validation.
Merge pull request #4591 from edx/benp/fix-attach-file

Fix false positive test in cms acceptance, harden attach_file helper.
Use create_item in xml_importer
Add make_course_key to modulestores, so that external clients don't need to assume a CourseKey subtype.
When creating a course during import, use that course key as the target course key.
Use a version_agnostic dest_course_id
Import Published content directly as Published, rather than a separate Publish call.

Conflicts:
	common/lib/xmodule/xmodule/modulestore/mixed.py
	common/lib/xmodule/xmodule/modulestore/xml_importer.py
Check both draft and published branches when asserting course equality
Use a consistent baseline course_key for checking item identifiers (to reduce differences due to different version numbers
Enforce that the block_id for courses in old-mongo is the same as the course run
Do comparison of item ids based just on the block_type and block_id