Added FindBugs and CheckStyle plugin, and added modified checkstyle configuration from http://code.google.com/p/google-api-java-client/source/browse/checkstyle.xml.

Still needs further configuration.
Custom checkstyle config, using almost everything up until Coding from http://checkstyle.sourceforge.net/checks.html.
Added all checks I found relevant from http://checkstyle.sourceforge.net/checks.html .
Merge pull request #6 from markuswustenberg/findbugs-and-checkstyle

Findbugs and checkstyle. Fixes #4.