astakos: Fix percentage bar bug in Usage tab
astakos: Wrong module names in MESSAGES_VIEWS_MAP

During the patch 'astakos: reorganize views' the module 'im/views.py'
was transformed into a directory and the code was moved to
'im/views/im.py'. Fix the wrong module names in MESSAGES_VIEWS_MAP
dictionary so that ASTAKOS_*_MESSAGES will be displayed.
branding: BRANDING_FONTS_CSS_URLS not defined

Define the 'BRANDING_FONTS_CSS_URLS' parameter in the config file.
ui: Fix missing cache invalidation param in rivets.conf.js url
deploy: Remove version dependencies

Remove dependencies to specific versions of snf-image and blktap-utils.
Rename blktap-utils to blktap-archipelago-utils
Add release date for v0.16
Bump version to 0.16rc2
Fix indentation issues in Changelog
docs: Fix typos