Make home directory and default user configurable

Use home= and user= parameters in the kernel command line to set
the home device and the default user

Signed-off-by: Claudio Matsuoka <cmatsuoka@gmail.com>

Makefile

@@ -1,5 +1,5 @@
 CC	= gcc
-CFLAGS	= -Os -Wall #-mno-push-args
+CFLAGS	= -Os -Wall #-DDEBUG
 LD	= gcc
 LDFLAGS	=
 LIBS	=