build: make sure /bin, /usr/bin are in $PATH

eg. on archlinux /bin is a symlink to /usr/bin, and /bin is not
in $PATH.  building rpm packages for openSUSE fails because the
chroot environment has /bin/rpm invoked as `chroot $BUILD_ROOT rpm`.
Merge pull request #100 from roman-neuhauser/sanitize-PATH

build: make sure /bin, /usr/bin are in $PATH
refactor pkg_set_type
it's UNDEFINED, not UNKNOWN...
- fix syntax error breaking qemu emulation check
refactor and fix find_recipe_files
do not use typeset, older bash versions do not understand it
- fix kiwi version check with new kiwis
- fix second local kiwi build, removing result dir first
- export .report instead of .channels from kiwi builds
refactor: add recipe_parse_options, move --stage to it
fix new kiwi version check...
s390 has virtio on the ccw bus (thanks Rudi)
move --kiwi-parameters option parsing into build-recipe

Also fix --kiwi-paramters=<arg> handling.