Pyowm

- New entity Station: represents a meteostation recording weather data
- New feature: search for meteostations around a lat/lon couple
- New feature: retrieve weather currently measured by a meteostation
- New feature: retrieve weathers currently measured by meteostations within a bounding box
- Can now query for weather forecasts based on geographical coordinates
- Can now query for weather forecasts based on city ID
- Support querying of extreme weather conditions in Forecaster convenience methods
- Enriched Weather class with methods to support data fields retrieved from meteostations
- Now supporting Unicode strings as parameters for all PyOWM public methods
- Increased test coverage

- Renaming of some functions in PyOWM public interface (**breaking change!**)
- Multilingual support for weather data descriptions
- Can now retrieve current weather from city IDs
- Can now retrieve weather history from city IDs
- Can now do toponyms to city IDs conversions using a registry
- Added more human-friendly utilities in Historian and timeutils modules
- Now checking code coverage via coveralls.io

Changelog versus 0.4.1 release:
- Users can inject configuration when instantiating the library
- Code is now compliant to PEP-8 guidelines
- Added XMLNS support to printed XML
- Refactoring of low-level utility functions
- Bug fixes

This releas adds the capability to specifiy a caching mechanism (either built-in or 3rd party) for caching OWM web API responses.