Fix DynamicSelectWidget.get_add_item_url() method.

Do not wrap self.add_item_link_args in an additional list because it
makes impossible to pass more than one arg (i.e. tuple or list of
args) to url resolver.

Change-Id: Idf6d5d1f27c9176f1de93a475e0f1abbae5ee275
Closes-Bug: #1297317
Add a centralized palette to Horizon

    With a centralized palette it will become easier to customize
Horizon design. Colors and file syntax are inspired by BootstrapV3
variables.less file

Change-Id: Iee0ed7cfea03fbba3385787646e55dd96a424327
Implements: blueprint centralized-color-palette
Co-Authored-By: miziel-r <robert.mizielski@cloudwatt.com>
Merge "Add a centralized palette to Horizon"
Merge "Fix DynamicSelectWidget.get_add_item_url() method."