Harden security for requests

- also harden MiqRequest, MiqRequestTask
- support yaml where symbols are stored (vs only strings)
- support yaml where only some values are invalid
  before: replace all values in a hash if any one value was invalid
- support password prefixes (vs whole value)
- ConfigurationEncoder#dump supports same options as load

https://bugzilla.redhat.com/show_bug.cgi?id=1151241
Merge pull request #799 from kbrock/fix_auth_service_key

Harden security for requests