Dynamically manage service states based on user defined conditions

Old event system has been replaced with a more generic condition
concept. The idea is that finit plugins may provide arbitrary
conditions that services may specify as dependencies that they require
to run.

In order to accomodate this, the service management has been
redesigned to use a state machine.

plugins/Makefile

@@ -8,7 +8,7 @@ LDFLAGS    += -shared
 ifneq ($(STATIC), 1)
 PLUGINS    ?= initctl.so alsa-utils.so bootmisc.so dbus.so hwclock.so \
 	      resolvconf.so urandom.so x11-common.so tty.so time.so   \
-	      netlink.so
+	      netlink.so pidfile.so
 DEPS       := $(PLUGINS:.so=.d)
 endif