Make keyvault optional, and disabled by default.

In some environments, the keys generated with this LWRP are not very
valuable.  If they are lost, generating new keys (and certs, and CSRs)
is okay.  Use of a key vault should be optional for such environments.

Disabling the key vault by default reduces the learning curve for new
users by making the vt-gpg cookbook an optional dependency.
Load certificate data bag items using search.

When a data_bag_item() call fails to load an item, messages are logged
at 'info' and 'error' levels and cannot be suppressed.  Missing items
isn't an error in this use case, so log output is improved by using
search() to look for the item.
Reopen existing resources to avoid CHEF-3694 warnings.
Don't include vt-gpg when the keyvault is disabled.

It will still be on the node (due to the metadata dependency), but we
shouldn't use it.
Mock search instead of data_bag_item in test.
Merge remote-tracking branch 'zts/quieten-logging'

* zts/quieten-logging:
  Mock search instead of data_bag_item in test.
  Reopen existing resources to avoid CHEF-3694 warnings.
  Load certificate data bag items using search.
Merge remote-tracking branch 'zts/make-keyvault-optional'

* zts/make-keyvault-optional:
  Don't include vt-gpg when the keyvault is disabled.
  Make keyvault optional, and disabled by default.
Bump version - 1.0.3
Make a note about running the tests.