Description of problem:
In some very limited use cases (including support situations) it may be necessary to upgrade or install RPMs during RHEVH runtime.  These modifications would be non-persistent since RHEVH filesystem is backed by an ISO image, but for some usages this is ok.

In order to support this in a controlled manner we need:
* wrapper around rpm command that remounts the rootfs as read/write
* does a dry run of the rpm install to determine what files would be installed 
  or modified and uses this info and a policy file to determine if the operation
  should be permitted
* creates a manifest file with sha1 hashes so that the pre and post hashes can 
  be compared

Certain rpms would never be applicable for this operation, such as the kernel and low level storage RPMs (lvm2, dmm)