IcedTea 2.4.7 using OpenJDK 7u55

Hi,
I've added recipes for IcedTea 2.4.7 using OpenJDK 7u55 due to the fact it contains lots of security fixes.

On my test platform (ARMv7) everything is working well:
```
localhost:~# java -version
java version "1.7.0_55"
OpenJDK Runtime Environment (IcedTea 2.4.7) (55b14-2.4.7)
OpenJDK Zero VM (build 24.51-b03, mixed mode)
```

Maybe some testing on other platforms to make sure it also works there would be a good idea.

So I'm awaiting your comments, test results and/or merge ;-)

regards,
Richard