ADD anonymous user

src/main/java/caosdb/datetime/UTCDateTime.java

src/main/java/caosdb/server/CaosAuthenticator.java

src/main/java/caosdb/server/CaosDBServer.java

src/main/java/caosdb/server/ServerProperties.java

...java/caosdb/server/accessControl/AuthenticationUtils.java

...a/caosdb/server/accessControl/CaosDBAuthorizingRealm.java

.../java/caosdb/server/accessControl/CaosDBDefaultRealm.java

...n/java/caosdb/server/accessControl/SessionTokenRealm.java

src/main/java/caosdb/server/accessControl/UserSources.java

src/main/java/caosdb/server/permissions/EntityACL.java

.../caosdb/server/resource/AbstractCaosDBServerResource.java

src/main/java/caosdb/server/transaction/Transaction.java