WIP: refactoring xml serialization

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

src/main/java/caosdb/server/FileSystem.java

...caosdb/server/converter/misc/AbstractContainerHelper.java

...db/server/converter/misc/MultipartContainerConverter.java

...caosdb/server/converter/xml/EntityXMLConverterHelper.java

src/main/java/caosdb/server/converter/xml/XMLParser.java

src/main/java/caosdb/server/entity/Entity.java

src/main/java/caosdb/server/entity/EntityInterface.java

src/main/java/caosdb/server/entity/WritableEntity.java

...ava/caosdb/server/entity/container/WritableContainer.java

...main/java/caosdb/server/entity/wrapper/EntityWrapper.java

src/main/java/caosdb/server/jobs/Job.java

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

...n/java/caosdb/server/resource/AuthenticationResource.java

...b/server/resource/transaction/AbstractEntityResource.java

...va/caosdb/server/resource/transaction/EntityResource.java

...aosdb/server/transaction/FileStorageConsistencyCheck.java

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