Consider supporting string wildcard operators

originaly created by Naweed:
https://github.com/hpcc-systems/HPCC-Platform/issues/3045

Please add the ability to query using wild card charecters '_' and '&' .

Please see the documention about wildcards at http://www.w3schools.com/sql/sql_wildcards.asp

Let me know if you want to discuss it.

Thanks
Naweed