Comment 6 for bug 1479018

Reviewed: https://review.openstack.org/208643
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=8303782f1e67c00f3000acf12773a7df7581fc61
Submitter: Jenkins
Branch: master

commit 8303782f1e67c00f3000acf12773a7df7581fc61
Author: David Lyle <email address hidden>
Date: Mon Aug 3 14:23:42 2015 -0600

    Move Horizon to pure plugin loading only

    The root cause of 1479018 was the mixed method for loading content in
    horizon. This patch moves horizon to load purely from enabled files.
    There are a couple of things that were required to allow this change.

    1) Adding a mechanism, can_register() to horizon/base.py to handle the
    configuration based loading checks that had been accumulating in the
    panel.py files. This is an optional static method in Panel to
    encapsulate such configuration (read settings) based panel loading
    logic. And added testing for and documentation for this addition.

    2) Create a numbering scheme for plugins. Moved the base dashboards to
    _1000_project.py _2000_admin.py _3000_identity.py _5000_settings.py.
    then populated the required panel_group and panel enabled files sparsely
    in those ranges. The sparseness is to allow for future additions.
    Additionally, I moved the already added Angular based panels next to
    their Django counterparts.

    Once the configuration loading was normalized, the bug reported in
    1479018 was resolved and tests work with plugins panels in all
    dashboards.

    Close-Bug: #1479018
    Partially implements: blueprint plugin-sanity

    Change-Id: I657e7ce37b2593a901a859cebf3d6ff8ada91941