Node Name is not set

On linux machines, I find that hostname is empty

content of controller-info.xml
```
xxxxxx
xxxxx

```

I don't know why node-name is blank because it set in the default.rb

https://github.com/Appdynamics/appdynamics-cookbooks/blob/master/attributes/default.rb#L5

Perhaps the string interpolation in the default.rb isn't working correctly.

Additionally it might be better to use chef node name since the hostname can change on the first chef boostrap

default['appdynamics']['node_name'] = Chef::Config[:node_name]

Read attributes/default.rb around line 5 and trace how appdynamics.node_name reaches controller-info.xml on Linux. Compare the configured value with the generated element and verify that the resulting XML contains the expected node name after a Chef bootstrap.

Written by the indexing model from the issue text.