logging: error reporting refactoring
- Refactors register_exception to use Flask application logging, and split functionality into a Python logging handler and formatter.
- Adds support for logging exceptions to Sentry.
- Disables email error reporting when in debug mode.
- Deprecates certain error logging function by moving them to the module where they are used. This is done to create a much simpler API.
- Fixes PEP8 errors.
Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>