cyclades: Validate VM metadata on create/update

* Check for VM max metadata items when updating/creating a single item.
* Check the length of metadata items when updating metadata items.
astakos: Fix a unicode bug in user-add

Fix a unicode bug in snf-manage user-add when the username contained
non-ascii characters.
astakos: Add checks for quota limits

Check that total (project) quota limit is no less than member limit;
and that both limits are not negative.
pithos: Recover from DB integrity errors

In Pithos+ atomicity is forced on the container level.
Hence, write operations in the account level can produce
integrity errors.

This commit handles these cases.

In PostgreSQL, a transaction is aborted
(and all the subsequent commands are ignored)
if an integrity error occurs.

Therefore, before performing an command
that can produce an integrity error,
a new savepoint is defined inside the transaction,
and after the command execution is rollbacked or committed
according to execution status.
docs: Update copyright date on docs
ui: Fix volume details editing controls position
ui: Update resource titles truncation length
astakos: Update checkbox label in terms acceptance form

the field description changed for field description clarity when
displayed in user management commands context resulting confusion when
appeared in terms acceptance form. Fixed by reverting field label in the
terms acceptance form class.