python: upgrade from 2.7.2 to 2.7.3

python: upgrade from 2.7.2 to 2.7.3

bin/python2 link is provided by the python install process,
so no need to create it.

rebase these patches to the newer code:
 fix_for_using_different_libdir.patch
 04-default-is-optimized.patch
remove this patch as it is upstream now:
 sys_platform_is_now_always_linux2.patch

Change default python version to 2.7.3 in the distro config

(From OE-Core rev: 5d92a95ea9b480235b7c9ca5949a681376eba725)

Signed-off-by: Nitin A Kamble <nitin.a.kamble@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>