burnin: Provide tests for snapshots

Extend burnin testing suite to provide snapshots functionality.

Closes #265
burnin: Delete temporary containers

Use kamaki's 'del_container' function with "delimiter='/'" in order to
delete temporary containers and all their contents.
astakos: Enforce message template strings to unicode

enforce provider message templates to unicode prior to the template
string manipulation. Most of the template variables are expected to be
in unicode thus mixing non-unicode template strings with unicode variables
is prone to encoding/deconding erros while rendering the auth providers
message templates.
deploy: Add 'ssl-cert-snakeoil' to the CA bundle

Deploy uses the ssl-cert-snakeoil certificate when configures apache.
Add the above self signed certificate to the system's CA bundle so that
kamaki can use it to verify the connections.
cyclades: Add --public option image/snapshot cmds

Add '--public' option to 'image-list' and 'snapshot-list' management
commands. Only fix stale help message of '--user' option.