revert "stick with pbr 0.5.19" commit

revert the following commit because it doesn't work with
the latest oslo.config which requires newer pbr.

|commit 205485e0520d8f37c49b66bbbf012a9448cd9367
|Author: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
|Date:   Fri Aug 30 14:08:49 2013 +0900
|
|    stick with pbr 0.5.19
|
|    the latest versions of pbr generate scripts which don't support
|    multiversion.  to avoid importing modules from older multiversion-aware
|    installations of ryu, we prefer multiversion-aware scripts.
|
|    Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
|    Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

the problem reported by Satoshi Kobayashi on ryu-devel.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
revert "support setup.py install with git archive tarballs" commit

revert the following commit because it has a side effect
to change pbr's version to ryu's version. (eg. 3.1)
it doesn't work with the recent version of olso.config
which requires pbr < 1.0.

|commit 55aa47489306ebb3bfa3307e3fa5a332007a58ed
|Author: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
|Date:   Fri Aug 2 14:33:40 2013 +0900
|
|    support setup.py install with git archive tarballs
|
|    Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
avoid pbr's non multi-version aware script

otherwise the latest ryu-manager can pick up older modules
if multiple versions of ryu is installed on a system.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
fix setup from a tarball again

this makes the following work again.

    DIR=$(mktemp -d)
    git archive --format=tar HEAD | (cd ${DIR} && tar xf -)
    cd ${DIR}
    python ./setup.py install

PBR_VERSION environment variable didn't work as we expected
because it unconditionally overrides versions for other packages
even if there are other ways to get their versions.  eg. PKG_INFO.

Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>