Replace util/Log.java with java.util.logging

Logger (from java.util.logging / jul) gives the user more control over which
statements are logged and which not, in a much more generic fashion then a custom Log.java.

It's easily possible to wrap the jul Logger into the Android Logger and have the same functionality. For example, I use the following JULHandler to pass all jul logs into Android's log system: https://bitbucket.org/projectmaxs/maxs/src/master/main/src/org/projectmaxs/shared/global/jul/JULHandler.java?at=master