Missing update on CONTRIBUTING.md

[clementval]

CONTRIBUTING.md file has not been updated with the new coding guiltiness applied with the new driver.

https://github.com/claw-project/claw-compiler/blob/master/CONTRIBUTING.md#java

So it should be updated or the coding style should be reverted to the original one.

[lxavier]

ok - I can take this updating the info to the new style (unless you prefer to revert the style, but this I cannot do).

[clementval]

Personally I prefer the previous coding style but if I'm the only one I can live with the new one.
If we revert the coding style I can do it easily.

[lxavier]

I let you decide, we are only going to do release and bug fix in the foreseeable future, so no strong preference on the style.