getColumnMetaData option

This pull request adds an `options` argument to connection.execute as optional 3rd argument.  This allows specification of `{getColumnMetaData:true}` as the options argument.

I added regression tests.  Existing tests pass.  I will need to modify the documentation if this is accepted but I'll wait until we agree on an API before I finish that.

Example will look something like this:
~~~javascript
...
    connection.execute(
        "SELECT * FROM person", [], {getColumnMetaData:true},
        function(err, results) {
            if ( err ) { ... } 
            // results.columnMetaData = [ { name: 'ID', type: 4 }, { name: 'NAME', type: 3 } ]
            connection.close();
        }
    );
    ...
~~~

Thank you