Update ViewModelViewHost.cs

Fixed type in format expression.
Merge pull request #704 from reactiveui/fix_typo_in_VMVH

Fix typo in ViewModelViewHost.cs
Disable laziness in ReactiveCommand in unit test runner
Why not
Disable laziness in unit test runner
Fix up the test suite
Inform users that Things Might Be Different
Merge pull request #705 from reactiveui/eager-in-unit-test-runners

Disable laziness in ReactiveCommand and ToProperty in unit test runner