Factor out Gson to an utility class.

Also, fix file encoding issues in 
IntervalBase.java
Initial attempt to use LevelDB for interval storage
Renate ActivityType to IntervalType.

Also, factory methods for IntervalType
Deserialization support for Dates
Create Intervals from text (JSON ATM)
Test writing and reading for the LevelDB persister
Merge branch 'refactor' of github.com:TestRoots/watchdog into caching

Conflicts:
	WatchDog/.classpath
	WatchDog/src/nl/tudelft/watchdog/logic/interval/IntervalTransferer.java
Intermediate commit for LevelDB integration

Most operations work except of finding a range of 
records.

ref: #40
Stylistic fixes
LevelDB is out, MapDB is in

ref #40
Implement and test interval persistence with MapDB

refs: #40
Merge branch 'master' into caching

Conflicts:
	WatchDog/META-INF/MANIFEST.MF
	WatchDog/src/nl/tudelft/watchdog/logic/interval/IntervalTransferer.java
	WatchDog/src/nl/tudelft/watchdog/logic/interval/active/IntervalBase.java
	WatchDog/src/nl/tudelft/watchdog/ui/infoDialog/InfoStatisticsDialog.java
	WatchDog/src/nl/tudelft/watchdog/ui/infoDialog/IntervalStatistics.java
	WatchDogUnitTests/src/nl/tudelft/watchdog/logic/interval/IntervalToJsonConverterTest.java
Merge branch 'caching'