Target API 19 (Android 4.4)
Remove unused import
Fix javadoc, use correct @link syntax
Suppress deprecation warning

because of using the deprecated Notification API
Replace Android Log with java.util.logging

java.util.logging.Logger gives the user more control over which
statements are logged and which not. Throwable.printStackTrace() calls
should be avoided, they are especially distracting when done in
non-fatal branches. Also combine successive log calls.
example: Add JULHandler for fine-grained logging control
Fix possible resource leak

by ensuring that FileOutputStream is closed.
example: add javadoc to JULHandler