[BC breaks] Refactoring, added weather history, removed autoloader.

- Weather history added, closes #3. 
- Autoloader removed, closes #6. It's strongly recommended to install this library via composer now.  
- Vendor name changed from `cmfcmf` to `Cmfcmf`.
- `new OpenWeatherMap()` constructor changed. The first parameter now is an instance of a class implementing `Cmfcmf/OpenWeatherMap/FetcherInterface`, which is responsible for fetching data from urls. Two fetchers are implemented, the old one using `file_get_contents($url)` and a new one using cURL. If you do not specify a fetcher, cURL will be used if it's available.
- The `copyright` string was removed from all classes and is now only available via `OpenWeatherMap::COPYRIGHT`.

Due to the bc breaks, this will be (pre-)released as v2.0.0(-rc1) (following *SemVer*). The "final" 2.0.0 release will follow after some days of testing.