Add base model for QueryBuilder
Fix Expressions names
Adding DSQL Grammar to Mule-Common.
Adding MetaData model visitor for filter fields operation and Modifying the query model to easy building and maintaining
Fixing compilation problem
Adding visitor model for creating string queries from model, ie QueryModel -> String
Adding DSQL -> QueryModel parsing.
Fixing metadata fields filtering and its tests
Adding ErrorNode handling to DSQL Parsing.
Small tests changes
Adding QueryOperator factory for DSQL -> QueryModel transformation. Adding tests.