Censusgeocode

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* Add static methods to module
* Update vintages and benchmarks.

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* Add support for address batch functionality, including to command line tool

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* Better error reporting when API is down.
* Use `requests[security]` to fix SSL 3 errors, bump required `requests` version.
* Combine Py 2 and Py 3 codebases.
* Add timeout parameter to `CensusGeocode.fetch` (thanks mxr)

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* Always yield a `ValueError` when Census API is broken.
* Internal refactor to simplify keyword arguments.

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* Improve deployment and fix readme

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* Add command line tool