MARMOTTA-440: implemented HTTP PATCH operation
MARMOTTA-440: Updated LDP-WebService tests (but they do not work...)
MARMOTTA-440: Some minor refactoring and javadoc
MARMOTTA-440: getResourceUri should be called only once per request
MARMOTTA-440: Handle UnsupportedMediaType for HTTP POST
MARMOTTA-440: Refactored LdpWebService and LdpService(Impl) to have only one transaction (RepositoryConnection) per request.