Engine: Fixes #3326, 3327: Changesets & Changeset History initial conversion

Modifications to UI for Changesets and Changeset History to function
within an engine.
Engine: Dashboard: few fixes for syncs, content views and promotions
Merge pull request #3256 from ehelms/engine-fix-3480

Engine: Fixes #3480: Correction to path for dashboard redirect.
Engine: engine-users - fixes #3331
Merge pull request #3254 from thomasmckay/engine-users

Engine: engine-users - refers #3331
Merge pull request #3247 from bbuckingham/engine-changesets

Engine: Fixes #3326, 3327: Changesets & Changeset History initial conversion
Merge pull request #3260 from bbuckingham/engine-dashboard

Engine: Dashboard: few fixes for syncs, content views and promotions
Engine: Authorization: use ::User vs User

Updating references to User to explicitly point to the core
user (::User)
Engine: fixes #3332: Roles initial conversion

This is the initial conversion of the katello roles ui to work
within the engine.  This includes CRUD actions for roles
and permissions.
Merge pull request #3258 from bbuckingham/engine-roles

Engine: fixes #3332: Roles initial conversion
Engine: fixes #3479 - db:seeds fails if readonly role exists and is locked but role has no permissions
Merge pull request #3255 from isratrade/3479_role_unlock

Engine: fixes #3479 - db:seeds fails if readonly role exists and is lock but role has no permissions
Engine: user.name incorrectly coming from pulp glue
Merge pull request #3269 from thomasmckay/engine-username

Engine: user.name incorrectly coming from pulp glue
Engine: engine-distributors fixes #3315

Engine: engine-distributors - updates to paths based on pull-request comments
Merge pull request #3267 from thomasmckay/engine-distributors

Engine: engine-distributors - fixes #3315
Engine: First round of test enablement.

This is the first in a series of commits that will enable our
test suite. The major changes this first commit brings are:

Addition of a test and spec task that can be run from Foreman proper.
To run the test suite, ensure the engine is loaded by Foreman and run either
'rake test:katello:test' or 'rake test:katello:spec' to run test unit or specs
respectively.

Conversion of Rspec test suite over to Minitest::Spec. The first file
changed was spec/models/activation_key_spec. This starts down a path
to unify on a single test framework - Minitest and bring our test suite
into congruence. The biggest changes are around the use of Mocha to handle
complex mocking and changing from 'should' expectations to 'must' and 'wont'.

Clean up of fixtures to reflect the table names they are associated with. Further,
each fixture must explicitly declare the class name associated in the katello_test_helper.
Automatic fixture label resolution wasn't working, thus opted for the use of Fixtures.identify.