Omnibot.State shouldn't be used anywhere anymore except as a GenServer
being started up in the supervisor.
Also, configuration must be loaded through Config.load/1 rather than
being constructed, because everything expects a tuple of {plugin,
config} now.
Finally, Omnibot.Core must be added to the configuration in order for
basic functionality.
Signed-off-by: Alek Ratzloff <alekratz@gmail.com>