Upgrade bootstrap-datepicker.js to latest version

Upgrade required to fix bug where date selection from previous and next year was wrong.

Closes-Bug: 1270884

Change-Id: I7cb6f7f5fd0a709cbf0c1325e832c92ec382b12c
Enhanced error message when router creation failed

Changed error message to show when the router creation
fails due resource quota restrictions.

Change-Id: If5a43d4132adc653694cc42c3d658ca2d88adc33
Closes-Bug: #1278482
Integration tests - page objects pattern

First pages:
* pageobject - the base page for all page objects
* loginpage - the login page object
* basepage - base class for all dashboard page objects
* adminpage
* projectpage

First test:
test_login - a basic scenario test:
* checks that the login page is available
* logs in as a regular user
* checks that the user home page loads without error

https://wiki.openstack.org/wiki/Horizon/Testing/UI

Partially implements blueprint: selenium-integration-testing

Change-Id: Icad82f5f7810c348ddc30cd767f1d3bf5ecb926e
Fix documentation about adding a new dashboard

Since blueprint plugin-architecture has been implemented,
the preferred way to add a new dashboard is a configuration
file, rather than an entry in INSTALLED_APPS.

This patch changes the developer documentation to reflect
this change.

Change-Id: I569b22b81da1442ec9bed13d50ebfccfff093ac7
Improve Host Aggregates handle method.

Added update conditions to the handle method (remove
and add hosts).
Previously, to perform an update, first all existing hosts
were removed and then all new hosts were added.
Now, the update method only
remove or add the changed hosts.
Added missing unit tests for the update.

Change-Id: I52acdd1226be504cf2d0cf029353dbf80e4aa01a
Closes-bug: #1287192
Merge "Enhanced error message when router creation failed"
Merge "Improve Host Aggregates handle method."
Merge "Fix documentation about adding a new dashboard"
Merge "Upgrade bootstrap-datepicker.js to latest version"
Merge "Integration tests - page objects pattern"