Set cinder volume clear
Fixes #102

Also adds variables for:
  * volume_clear_ionice
  * volume_clear_size
resoves the rootwrap and MTU issues within neutron
Merge pull request #128 from hughsaunders/set_volume_clear

Set cinder volume clear
Merge pull request #129 from cloudnull/neutronMTU

Resolves the rootwrap and MTU issues within neutron