Checkstyle

[Joern Kottmann <ko...@gmail.com>]

Hello all,

we added the checkstyle maven plugin to the build.

Please let us know what you think about the enforced rules and what you
think should be added.

For some rules it is good to fail the build, this will make it easier
for us to perform code reviews, because travis will then by itself
report on style violations. This means we can just spent our time
reviewing the actual changes without discussing style violations.

J�rn