setup git committer info in Travis

pkg/ Makefiles based on `Makefile.git` fail in Travis when attempting to apply patches with `git am` because no committer info is set.
This patch adds a dummy Travis username and mail in the 'install' step to satisfy git.
Merge pull request #1379 from benpicco/setup_git

setup git committer info in Travis
add olsr2
add metrics

Implement link metrics and differentiate between flooding and routing MPRs
add olsr2 example application