utils: new Memoize

* Removes unnecesary duplicated memoize.

* Adds InstanceMethodMemoize for memoizing instance methods.

* Renames Memoise to Memoize.

Signed-off-by: Mateusz Susik <mateuszsusik@gmail.com>
Are you sure using same `*args` in `__call__` and `wrap`?