Add 'rlike' and 'regexp' to accepted SQL query operators.

[Weeblewonder]

Tried using 'rlike' and 'regexp' with Musician::where('instruments', 'regexp', '(Vocals|Bass)') but found that in Database/Query/Builder where() only accepts certain operators.
So I suggest to add these in, not sure if its appropriate as I dont know if rlike/regexp are MySQL only and query builder is meant to be abstract.

[taylorotwell]

Since those are vendor specific expressions, I think using whereRaw would be the best option in this case.