configure nodemanager java memory arguments

Add the possibility to configure nodemanager jvm memory arguments.
Hiera example for jrockit-jdk1.6.0 : 
```
nodemanager:
 'nodemanager11g':
  nodemanager_address: "10.10.10.10"
  domain_name: Wls1036
  nodemanager_java_mem_args: "-Xms32m -Xmx200m"
```
```
$nodemanager = hiera_hash('nodemanager')
create_resources(orawls::nodemanager, $nodemanager)
```
default to ```-Xms32m -Xmx200m -XX:PermSize=128m -XX:MaxPermSize=256m```