Log Message:
Add py-cached property
A cached-property for decorating methods in classes.

History:
1.2.0 (2015-04-28)

    Overall code and test refactoring, thanks to @gsakkis
    Allow the del statement for resetting cached properties with ttl instead
    of del obj._cache[attr], thanks to @gsakkis.
    Uncovered a bug in PyPy, https://bitbucket.org/pypy/pypy/issue/2033/
    attributeerror-object-attribute-is-read, thanks to @gsakkis
    Fixed threaded_cached_property_with_ttl to actually be thread-safe, thanks
    to @gsakkis

1.1.0 (2015-04-04)

    Regression: As the cache was not always clearing, we've broken out the
    time to expire feature to its own set of specific tools, thanks to
    @pydanny
    Fixed typo in README, thanks to @zoidbergwill

1.0.0 (2015-02-13)

    Added timed to expire feature to cached_property decorator.
    Backwards incompatiblity: Changed del monopoly.boardwalk to del
    monopoly['boardwalk'] in order to support the new TTL feature.