Make user loading memoize the authenticated user instance

Signed-off-by: Sam Phippen <samphippen@googlemail.com>
Bump libnemesis submodule version

Signed-off-by: Sam Phippen <samphippen@googlemail.com>
Better messages to users whilst things are happening

Signed-off-by: Sam Phippen <samphippen@googlemail.com>