Updating slide content and notes
Update sample code

* Add factorial.erl and funprog.erl source examples
* Update algebraic_properties.erl source with intentionally breaking code
* Add type specs to factorial module and rename function
* Add type spec for fun funprog:compose/1
* Add either Erlang module
* Rename prop_* functions with better names
* Update algebraic_properties.erl source with intentionally breaking code
* Add factorial.erl and funprog.erl source examples
Update work URL to public GitHub repo in README.md