Edit filtering

So here's my changes to allow for a way to change the default "where/orwhere" conditions in the filtering to something else.
If you have a column that uses aggregate functions (like group_concat) and you need to filter by it, then the query needs to use "having" instead of "where". 

Simply add 
```
->filter_column('col_name', 'having')
```

These changes are not tested properly. I tested it only on the project where I needed them and I'm not sure if something else got broken in the way.

PS: Sorry for any mistakes made. This is my first pull request.