buildbot{,-slave}: update 0.8.8 -> 0.8.10

Build tested. Source distribution is now on pypi instead of googlecode.

(cherry picked from commit 99eab9f1e2e3fcf4497b9ea0ffd54918a6b9299b)
buildbot-slave: align attrname with pkgname

Keep old attrname (buildbotSlave) around for backward compatibility.

(cherry picked from commit 1b396c7ae959f57295a65c170b5a238160ac64d3)