Fix #155: add support for env:/a/bc to service/run/task

This patch makes it possible to create a service with optional
arguments, similar to the systemd EnvironmentFile= setting.

The major difference to systemd, is that Finit does not attempt
to start a service if it cannot find the env. file, unless it
is prefixed with '-'.

Example:

    /etc/default/syslogd:
    SYSLOGD_OPTS="-m0 -r 128k:10 -s"

    /etc/finit.d/enabled/syslogd.conf
    service env:-/etc/default/syslogd syslogd -F $SYSLOGD_OPTS

Only downside, right now, is that changing the contents of the file
/etc/default/syslogd does not mark the syslogd.conf as modified and
a subsequent `initctl reload` will *not* restart syslogd.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/svc.h

@@ -134,6 +134,7 @@ typedef struct svc {
 	char	       cmd[MAX_ARG_LEN];
 	char	       args[MAX_NUM_SVC_ARGS][MAX_ARG_LEN];
 	char	       desc[MAX_STR_LEN];
+	char	       env[MAX_ARG_LEN];
 
 	/*
 	 * Used to forcefully kill services that won't shutdown on