Code documentation

More code documentation. Reworded parts of CONTRIBUTING.rst
Corrected the project name in LICENSE
Build up to v0.2.0

* Fix issue with odd-numbered population that causes an off-by-one error in the
  population size
* Set default ga selection function to tournament_selection (converges faster
  than random_selection for the examples)
* Created examples to show how to use the library
* Modified HISTORY to reflect changes (pypi upload, new version)
* Started versioning (better late than never); copied jeffknupp’s
  update_version.sh from sandman

    selected versioning standard: major.minor.micro (e.g. 2.1.5)
    - major => big changes that may break compatibility
    - minor => new features
    - micro => bug fixes
Make update_version.sh executable