$or filter doesn't group together conditions

[jayalfredprufrock]

This is a bit of a security issue. (See feathersjs/feathers#404)

I was able to fix this by altering a few lines in the knexify() method to use knex's grouping capabilities. My fork is all screwed up right now so I can't submit a PR at the moment, but I wanted to go ahead and post the fix here:

// line 69
if (method) {
    if (key === '$or') {
        return query.where(function(){
            value.forEach(condition => this[method].call(this, condition));
        });
     }
     return query[method].call(query, column, value);
 }

[kaiquewdev]

#73

[daffl]

This should be closed now thanks to @kaiquewdev #73 and #75