Added method fill on HList singleton object

- Added object hlistsingleton in ops
- Added Fill definition and implicits in hlistsingleton
- Added method fill to HList singleton object
- Various tests of HList.fill
Added method fill on Tuple singleton object

- *Added Tuple singleton object in shapeless namespace*
- Added object tuplesingleton in ops
- Added Fill definition and implicits in tuplesingleton
- Added method fill to Tuple singleton object
- Various tests of Tuple.fill