python: Add support for peer umask option
conf: Update default configuration with umask option
peer.c: Initilize local signal only once
archipelago: Add timeout to vlmc lock acquire

Add timeout to vlmc lock acquire. Set it by default to 15 seconds.
mapper: Restore correct map state when destroying fails
archipelago: Add umask config option

Add umask config option and make archipelago tools use it.
docs: Update upgrade-0.4 guide