Add viewable/sendable log

[ironjan]

Based on #99 it would be nice if there was a viewable application log somewhere.

This log should contain the most important events:

• sync start/end
• sync errors
• crashes/errors
• important events (switching allergens on/off etc.)

[ironjan]

https://code.google.com/p/android-logging-log4j/ <- seems to be the solution.

Above code configures the log4j system with some default settings e.g.

• file appender and LogCat appender
• rotating logs and corresponding backup files and file sizes
• default log output pattern

Perhaps com.noveogroup.android:android-logger would need to be replaced.

[ironjan]

It seems that the library mentioned above is not maintained anymore.