Split examples into separate modules for cats and scalaz

[andyscott]

The examples module is currently for cats only. A new examples module should be added for the scalaz version of iota. The cats examples can be ported to Scalaz, and new Scalaz specific examples can be added.

Note:
Most of the core code is using the "yax" trick to cross compile. This causes the code to be somewhat convoluted. This is less ideal for example code, which should be as clean as possible. This is why it's preferable to have two separate example modules tailored for each underlying lib, instead of one combined one.

Things to do:

• create a new example module for scalaz
• port over the basic cats examples to scalaz
• add scalaz specific examples
• update readme to link correctly to the different examples

[andyscott]

Addressed by #90