fix up comment in unary, fix up delete-tests
Adding having clause and tests
Add sql.functionCall.  Example: sql.select(sql.functionCall('concat', 'hello', 'world'))
Adding in shortcut for standard functions, next step is to figure out how to load dialect specific functions
Merge pull request #94 from yc662/havingClause

Having clause, used to filter aggregations
Merge pull request #91 from yc662/function

Introduce the concept of functions
Bump version