add Scala functor example

[0lejk4]

Provided Functor example for a Scala language. Functor is implemented using typeclass in Scala and usually is provided by some library like Cats or Scalaz where it is much more complicated than in this simple example.

[0lejk4]

Sorry, didn't see that someone already provided with Scala examples. Should check Pull Requests first next time) But just in case i`ll reopen it.

[tshemsedinov]

@DzyubSpirit can you please review this?

[DzyubSpirit]

Yeah, sure :)

[DzyubSpirit]

This PR tries different from #9. I would say #9 approach is more like Javascript and this PR is more like Haskell in terms of functor definition. #9 and Javascript just implement map method in every functor type (Maybe, Either, Array...). This PR and Haskell typeclasses additionally create Functor entity which is an abstraction of more concrete types (Maybe, Either, Array...)
That makes this PR approach more difficult but at the same time more type safe.
I think both of the #9 should be landed as it is and this code should go into advanced folder

[DzyubSpirit]

Suggested change

	print(just("2").fmap(_.toDouble).fmap(a => a + 3))
	println(just("2").fmap(_.toDouble).fmap(a => a + 3))

[0lejk4]

Just added README, refactored names, moved to Scala/Advanced folder and added comments about the second example, please check it once more. @DzyubSpirit

[DzyubSpirit]

Good work!