Replacing calls to `Exception#printStackTrace()` with Java logging.

This will keep output cleaner, especially in Android where logging and stdout are mixed.
Replacing some tabs with spaces for consistency.
Use Log#log(Level, String, Throwable).

Additionaly, increase log level of exceptions from FINE to WARNING.
Merge pull request #139 from benjamin-bader/no-exception-printing

Replacing calls to `Exception#printStackTrace()` with Java logging.