Implemented Bridge and refactored EntityResource

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

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

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

...main/java/caosdb/server/resource/EntityOwnerResource.java

...ava/caosdb/server/resource/EntityPermissionsResource.java

.../java/caosdb/server/resource/PermissionRulesResource.java

src/main/java/caosdb/server/resource/RolesResource.java

src/main/java/caosdb/server/resource/UserResource.java

src/main/java/caosdb/server/resource/UserRolesResource.java

src/main/java/caosdb/server/resource/XMLServerResource.java

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

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

...rver/resource/transaction/handlers/FileUploadHandler.java

...aosdb/server/resource/transaction/handlers/IDHandler.java

.../server/resource/transaction/handlers/RequestHandler.java

...tion/handlers/RetrieveGlobalEntityPermissionsHandler.java