main: Always attempt load the config

main: Always attempt load the config

Rather than loading most of the time in main() (and failing if it fails),
and then also loading the config in "repo init" (and tolerating its absence),
always attempt to load the config, and only fail if we end up missing bits of
information that we need.

This will set the stage for unifying the configuration and the
command-line options.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>