Fix NullReference exception when connecting to a WAP endpoint with self-signed or otherwise "bad" certificate.

Correct behavior is still to fail, but to provide a sensible exception instead of NullReference.
Fixed bug with provided credentials not being configured in newly-created WAPack VMs.
Fix name of parameter in New-WAPackQuickVM help XML. VMCredentials -> VMCredential
Merge remote-tracking branch 'upstream/dev' into dev
Merge pull request #2207 from spclark/dev

Several small fixes for WAPack IaaS cmdlets