Update NOTICE file after removing obsolete Example Data module (#69).
Remove observation identifier from local cache:
- because it can result in a big cache file if each observation has an observation identifier, e.g. 150000 observations with identifier ~ 15 MB cache file.
- only used by DeleteObservation to check if the requested identifier is valid. Now the database is queried and the invalid parameter exception is thrown if no observation was found.
Merge pull request #70 from CarstenHollmann/feature/remove_observation_identifier_from_cache

Feature/remove observation identifier from cache