RepositoryStartupServlet constructs FileStore incorrectly

The RepositoryStartupServlet in trunk (I am using release/tag 2.8.0 in testing) incorrectly constructs FileStore by passing 256*1024*1024 in the maxFileSizeMB parameter; as documented, this parameter's value is multiplied by 1048576 again in FileStore(BlobStore, File, NodeState, int, int, boolean) which causes the integer to overflow.

The overflow causes the FileStore's maxFileSize to be 0, which unsurprisingly causes a crash later on in initialization of the store. A simple patch is attached to resolve this issue.