[release] Update version to 1.0.0+ post release

Signed-off-by: Marty Connor <mdc@etherboot.org>

src/Makefile

 VERSION_MAJOR	= 1
 VERSION_MINOR	= 0
 VERSION_PATCH	= 0
-EXTRAVERSION	=
+EXTRAVERSION	= +
 MM_VERSION	= $(VERSION_MAJOR).$(VERSION_MINOR)
 VERSION		= $(MM_VERSION).$(VERSION_PATCH)$(EXTRAVERSION)
 CFLAGS		+= -DVERSION_MAJOR=$(VERSION_MAJOR) \