Replace the code to check for Option != None with Option.isDefined call in Scala code.

This hopefully will make the code cleaner.
Merge pull request #490 from hsaputra/modify_checkoption_with_isdefined

Replace the check for None Option with isDefined and isEmpty in Scala code

Propose to replace the Scala check for Option "!= None" with Option.isDefined and "=== None" with Option.isEmpty.

I think this, using method call if possible then operator function plus argument, will make the Scala code easier to read and understand.

Pass compile and tests.