Publish to Maven Central

[fbricon]

...so that flogger can be used by, well, everybody outside Google.

If flogger is already published to another public Maven repository, then please add some documentation on how to consume it.

[ronshapiro]

We're on it :)

I'm going to move Dagger's jarjar rules into google/bazel-common so that we can share them here - that should be the last step