Some variables should be declared as Long not String. HappendAt, Nanotime
More tests
Merge branch 'master' of https://github.com/kesapojat/tmc-snapshot-api

Conflicts:
	src/main/java/fi/helsinki/cs/tmc/snapshot/api/model/SnapshotEvent.java
	src/main/java/fi/helsinki/cs/tmc/snapshot/api/service/SnapshotDiffPatcher.java