Revert "[maven-release-plugin] prepare for next development iteration"

This reverts commit af7498870a4eed0f6e4b9fe37cc69edc022d0d8c.
Revert "[maven-release-plugin] prepare release v0.8.1-incubating"

This reverts commit c88a9916a183e7a57b53537531620bbde6d8869a.
Merge pull request #246 from pwendell/master

Add missing license headers

I found this when doing further audits on the 0.8.1 release candidate.
(cherry picked from commit 6169fe14a140146602fb07cfcd13eee6efad98f9)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>