Execute stored procedure

I extended edge-sql to execute stored procedures. I am using the SQL prefix EXEC to indicate that the SQL statement is the name of a stored procedure. For example:

```javascript
var edge = require('edge');
var selectUserByUserName = edge.func('sql', function () {/*
    EXEC dbo.SelectUserByUserName
*/});
selectUserByUserName({userName: 'zach'}, function (error, result) {
    if (error) { throw error; }
    console.log(result);
});
```

I refactored the ExecuteQuery method to extract out the code for setting the parameters and processing the result set. This code is now being shared by the method to execute the SELECT statement and the code that executes a stored procedure.