Implementing accordion navigation

Left hand side navigation is now an accordion with collapsable
dashboards and panel groups.

The project and region pickers have been relocated to the header.
They will be further enhanced in a future bp.

The help link and settings link have now been placed in a user
dropdown as well.

The page header text is still preserved and now sits above the
main content. This information is generally redundant with the
table headers or the panel selected in the left hand navigation,
and should be considered for removal in a different bp.

Implements blueprint navigation-enhancement

Change-Id: I9588cabdf4ce41bd08cadff780b1a87f73dbbea5
Add disk config option support

Allow servers to be created, resized, and rebuilt with the
disk_config option.

Change-Id: If8d940d8aaf583e49d9e3f528591dcf167021e26
Implements: blueprint disk-config
Sort requirement files in alphabetical order

This makes code more readable, and can check whether specific library
in the requirement files easily. We enforce the check in pep8, We also
add the tools for checking requirements.txt and test_requirements.txt.

Change-Id: Ia0a24553b7a5204faf6413c17dae6ba6aae2b5e8
Closes-Bug: #1285478
Basic support for Cinder v2

Change-Id: I6540720866c9005cf9537fe5b3a241f769529b3a
Implements blueprint: cinder-v2-horizon
Closes-Bug: #1226944
Plugin-based panel configuration

This is an extension to the plugin-based dashboard configuration.
It adds support processing panel configuration configuration file
in the openstack_dashboard/enabled/ directory.

Panels can be added, removed to/from the panel group of a dashboard.
It also provide the ability to update the default panel of the
dashboard.

Change-Id: I2d7adfb8045c244ec063a6741e3b9fe21c188525
Implements: blueprint plugin-panel-config
Merge "Basic support for Cinder v2"
Merge "Implementing accordion navigation"
Add flavor extra spec key templates

Add a variety of common keys in a dropdown to help users
add flavor extra keys.

Change-Id: I1738c65887cc165255a027f82474a33c5efe3218
Implements: blueprint flavor-extra-specs-templates
Merge "Add disk config option support"
Merge "Add flavor extra spec key templates"
Merge "Sort requirement files in alphabetical order"
Merge "Plugin-based panel configuration"