fence_vmware_soap, fence_ovh: Caching problem with SOAP library

Both fence agents are built on top of SUDS library which creates a cache file. Unfortunately,
it is not yet possible to completely move cache or remove it. Due to possible security issue (symlink
vulnerability) we have decided to solve this problem as simply as possible. So '/tmp' was changed to an
automatically generated temp directory which is removed at the exit of fence agent as we won't reuse it anyway.

Resolves: rhbz#1014000