Change build system to autotools

Change build system to autotools

This patch is largely based on Richards original RFC.

The major differences to the RFC patch are:
 - Add missing sumtools & mtdpart targets
 - Fix name of mkfs.jffs2 target
 - Add missing subdir-objects option for non-recursive make
 - Move all automake options to configure.ac
 - Add manpages to install target
 - Make XATTR & LZO support configurable
 - Install binaries to sbin directory like in the old build system
 - Install flash_erase wrapper script
 - Add files missing from distribution target

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Signed-off-by: Richard Weinberger <richard@nod.at>