Allow UpdateFactory to support arbitrary syntaxes
i.e. Remove the restriction that the syntax must be SPARQL 1.1/ARQ
The relevant method already contains a later check for the case where no parser is registered so the more restrictive check is unecessary
and it restricts users from using extended syntaxes

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1625242 13f79535-47bb-0310-9956-ffa450edef68