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
Modify VixDiskLib Client/Server to Use new ffi-vixdisklib gem

Change the VixDiskLib client/server DRb code to use the
ffi-vixdisklib gem instead of the existing code in vixdisklib_api,
vixdisklib_server, and the contents of the VixDiskLib_FFI directory.
The highest level ffi-vixdisklib wrapper, miq_wrapper, will be used
to mirror the previously existing functionality.  Remove previously
used code which is replaced by the gem code.
Modify VixDiskLib tests to use ffi-vixdisklib gem

Modify two VixDiskLib tests, cookedTest.rb and vixDiskModTest.rb,
to use the new ffi-vixdisklib gem.
VixDiskLib tests for the ffi-vixdisklib gem

Modify two VixDiskLib tests, cookedTest.rb and vixDiskModTest.rb,
to use the new ffi-vixdisklib gem at the uppermost miq_wrapper layer.

Add a new test, api_test.rb, to use the ffi-vixdisklib gem at the middle
api_wrapper layer.