Right now, the representation of an epiweek is like a dictionary at some places (when returned from a few functions) and two independent integers at other places (when ingested in functions). Similar to mmwr-week (the js version), we can make it a class that goes like Epiweek(2014, 23).

There are the following benefits:

1. Its cleaner to have a single standard
2. The Epiweek class can then be made hashable (dicts are not) so it will work nicely with pandas.Series which gets used a lot while working with the data we have.

On the downside, the projects depending on this might have to either:

1. Pin their version as pymmwr == 0.1.0 (preferred) or
2. Change the code if thats not a lot of problem.

As far as I know, other than some ensemble repositories (where I can pin the version), there is forecast-repository where this is getting used. @matthewcornell, thoughts?