Create a persistent BitSet data structure

[l0rinc]

BitSet is extremely useful when you want to test the presence of some enumerable entity, i.e. a compact Set of Booleans.
We might want a pure one in Javaslang also.

It could be based on Scala's or Haskell's implementations.

[danieldietrich]

Nice idea. Basically we align to Scala (type hierarchy and naming). Looking at Haskell is better in terms of impl details because it is more clean/pure. However, when it comes to recursion we use iteration with mutable local method vars instead.

[ruslansennov]

@danieldietrich @paplorinc please take a look on this skeleton: b63602e (copied from Scala implementation)

[ruslansennov]

#1334