SPARQL - add INSERT and DELETE support for SPARQL Update

[bplatz]

Now that we support insert and delete in FlureeQL, we can translate the corresponding SPARQL syntax into it:

This SPARQL update statment:

DELETE { ?person <http://xmlns.com/foaf/0.1/givenName> 'Bill' }
INSERT { ?person <http://xmlns.com/foaf/0.1/givenName> 'William' }
WHERE
  { 
    ?person <http://xmlns.com/foaf/0.1/givenName> 'Bill'
  } 

Should parse to this FlureeQL:

{:delete ["?person" "http://xmlns.com/foaf/0.1/givenName" "Bill"]
 :insert ["?person" "http://xmlns.com/foaf/0.1/givenName" "William"]
 :where  [["?person" "http://xmlns.com/foaf/0.1/givenName" "Bill"]]}