Merge pull request #229 from matthesrieke/develop

Develop
Merge pull request #232 from matthesrieke/develop

move unregistration of listener to onDestroy.
Merge branch 'bugfix-0.9.1' into develop
allow adjustment of sampling rate via preferences
remove serialization of service state
some verbose logging on lifecycle methods.
improve memory usage on db storage of measurements
reduce memory usage: do not hold measurements in an ArrayList
check for existing properties on MAF calculation
refactoring: do not use a reference to a Track object in CommandListener
first prototype "track as reference"; fix issues with tests
fix UI Activity test (IllegalStateException regarding Theme/Sherlock)
shutdown commandlistener before init.

might exist multiple times - depending on race conditions.
Merge pull request #234 from matthesrieke/feature-track-as-reference

Feature track as reference
StreamTrackEncoder and some periphering stuff
Let TrackDAO and Util use the StreamTrackEncoder
add some debugging statements
fix issue with sampling rate in config (1s -> 1ms; not converted)
change to FileEntity in order to be able to repeat a request
Merge pull request #236 from matthesrieke/feature-streaming-json

Feature streaming json