Code convention

Hi I added the mentioned( #4 ) google-style formatter. Taken from [here](https://code.google.com/p/google-styleguide/source/browse/trunk). Since IntelliJ also can import eclipse profiles perhabs it makes sense to just keep track of one file if we want to make some changes on it. That one mentioned in this PR is the original one. I also updated the Contribution.md any suggestions are welcome.
Hi @vboctor ,
keeping only the .idea/codeStyleSettings.xml and discarding the rest may leed us to problems because you cant just "open" the project in intelliJ you need to import it as maven-project. Since you do so the content of .idea may get overwritten (a message is shown). I think if we dont want to put the referenced files under version-control we need to implement the formatter as eclipse standard and it then can be imported manually.