Clean up nova-data role

names, whitespace, logic changes, failed_when.
Failed in CI:
```
TASK: [nova-data | update various lines in libvirtd.conf] ********************* 
Thursday 06 November 2014  14:00:44 -0800 (0:00:39.780)       0:22:13.724 ***** 
changed: [173.247.105.5] => (item={'key': 'lvopts', 'value': {'regexp': '^libvirtd_opts', 'line': 'libvirtd_opts="-d -l"'}})
fatal: [173.247.105.5] => A variable inserted a new parameter into the module args. Be sure to quote variables if they contain equal signs (for example: "{{var}}").
changed: [173.247.105.7] => (item={'key': 'lvopts', 'value': {'regexp': '^libvirtd_opts', 'line': 'libvirtd_opts="-d -l"'}})
fatal: [173.247.105.7] => A variable inserted a new parameter into the module args. Be sure to quote variables if they contain equal signs (for example: "{{var}}").
changed: [173.247.105.6] => (item={'key': 'lvopts', 'value': {'regexp': '^libvirtd_opts', 'line': 'libvirtd_opts="-d -l"'}})
fatal: [173.247.105.6] => A variable inserted a new parameter into the module args. Be sure to quote variables if they contain equal signs (for example: "{{var}}").
```