Rewrite pieces of code deprecated by Django 1.7

The mimtype argument of HttpResponse, SimpleTemplateResponse,
TemplateResponse, and render_to_response was removed; one should
use content_type instead

Change-Id: I62214c37264845dbabf006a32616e894c4ac9e3a
Closes-bug: #1266676
Partially-impelements: blueprint django-1point6
Add volume extend functionality support

Cinder now has the ablity to extend a volume, This functionality
should be exposed through Horizon.

Change-Id: Iff26453fd0a83af97fad4adabbcd53f646a15e51
Implements: blueprint volume-extend
Sync OPENSTACK_KEYSTONE_DEFAULT_ROLE with keystone

For now, keystone default role is _member_, while horizon set
OPENSTACK_KEYSTONE_DEFAULT_ROLE to Member. It will really be user
friendly to modify horizon default value to _member_ to sync with
keystone's default setting.

Change-Id: I55d15e6cfb74e52e933c5a44efd6c27930415738
Closes-Bug: #1264228
Make table_actions style work with buttons

Change-Id: I4470d50567e4fa92370ee8573047f5d717b74962
Closes-Bug: #1269653
Revert "JSHint integration"

This reverts commit 7711a78ac4365a04d49a69ca5238b7c2fc045f15.

Closes-Bug: #1270764
Change-Id: I259384716089b1cdb2c66e6777d54848de5fa58d
Merge "Revert "JSHint integration""
Merge "Rewrite pieces of code deprecated by Django 1.7"
Merge "Add volume extend functionality support"
Merge "Sync OPENSTACK_KEYSTONE_DEFAULT_ROLE with keystone"
Merge "Make table_actions style work with buttons"