admin: Add setting for enabling charts

Add a setting (ADMIN_ENABLE_CHARTS) for enabling the charts presentation
of Astakos/Cyclades resources. This setting will default to False.

The charting software that is used is Highcharts by HighSoft AS. It is
due to the licensing nature of Highcharts that charts are disabled by
default. You can view the Highcharts license [1] and the accompanying
FAQ [2], to decide whether to enable it or not.

[1]: www.highcharts.com/license, http://shop.highsoft.com/highcharts.html
[2]: http://shop.highsoft.com/highcharts.html,
     http://shop.highsoft.com/faq/non-commercial
snf_django: Associate two more apps with Astakos

The apps "quotaholder_app" and "auth" have models that are stored in the
Astakos database, and should thus be included in the check of
`select_db()`.
docs: Use correct router for admin
admin: Remove obsolete admin router

The admin router has been superseded by the SynnefoRouter of snf_django.
branding: Common cross app branding setting related to web fonts urls

Introduce BRANDING_FONTS_CSS_URLS setting to support loading of webfont
related css files from custom locations. By default fonts are loaded
from Google CDN servers. An essential utility setting for intranet
Synnefo deployments.

The `undocumented` setting UI_FONTS_BASE_URL is deprecated and no longer
used.
cloudbar: Apply condition on whether or not to load webfont css files
branding: Update branding-settings.conf

include default values and description for BRANDING_FONTS_CSS_URLS
setting.
ui: Remove deprecated setting from ui .conf file
webproject: Use branding webfonts css setting in 403/404/500 templates
cloudbar: Remove debug statements
cloudbar: Include url invalidation parameter based on synnefo version

make cloudbar.{js,css} unique per version to enforce client reload
between previously cached versions after synnefo upgrades.
cyclades: Check that volume type ID is an int

Make `flavor-create` command to check that the given volume type ID is
an integer.
pithos: Set v0 size on Archipelago request
cyclades: Update vncauthproxy requirement

Require vncauthproxy>1.5.
docs: Update docs for 0.16
Add archipelago to Pithos backend dependencies
Merge pull request #214 from cnanakos/release-0.16

Update docs and fix Pithos Archipelago request
Add NEWS for Synnefo 0.16rc1
docs: Update 0.16 upgrade guide
docs: Link v0.16 Chaneglog and NEWS in admin guide