Set APPEND_TO_VERSION and undo earlier blunt version hacks; bump release

APPEND_TO_VERSION is what make-kpkg uses.  D'oh.

Update to release 3; new build should name /boot/vmlinuz-*,
/lib/modules/*, etc. correctly.
Put upstream kernel version in ORIGKERNELRELEASE & fix generated paths

Several generated paths have a component like '3.5.7';
'3.5.7-xenomai-2.6.2.1' won't do:

CONFDIR:  where the Ubuntu upstream kernel config is saved
FLAVOR_CONFIG_FILE:  Xenomai kernel configs
XENOMAI_PATCH:  the i-pipe and Xenomai kernel patch