Several changes:

Common:
- Normalized report_coverage_*.sh scripts, and temporarily summarized results in device one for testing purposes.
- Adapted run_tests_locally.sh script for testing purposes
- Improved message synthesis of ServiceException

Context:
- Improved ConfigModel helper functions

Device (intermediate backup):
- Removed DataCache since it reduces readability of the code. Moved database one level up.
- Improved ServicerImpl and moved DataCache functionality over there.
- Added condition to prevent AddDevice request from carrying a configuration.
- Multiple pre-work required for processing configuration differences in DeviceServiceServicerImpl.