remove known_status from events table. Not used for queries/filters

bindings/java/src/org/sleuthkit/datamodel/AbstractFile.java

bindings/java/src/org/sleuthkit/datamodel/SleuthkitCase.java

...ngs/java/src/org/sleuthkit/datamodel/TimelineManager.java

...a/src/org/sleuthkit/datamodel/timeline/TimelineEvent.java

tsk/auto/db_postgresql.cpp

tsk/auto/db_sqlite.cpp