Partially fixes#6094.
Prior to this when passing the same query and CQ name in a CREATE
CONTINUOUS QUERY command an error would be returned. This means the
command was not behaving in a similar way to other commands.a
Now when running the command with the same CQ name and query string no
error will be returned. Note, this change does not parse the query, it
simply compares a normalised query string to the existing one on the CQ.
dcb6e318e9