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.
I wonder if we should ignore .idea by default and just add the exceptions that we need.  This way we don't end up including stuff we don't know about or newly introduced stuff by default, but be selective of what we want in source control.