This commit adds/changes the following for SmartOS guests:
- modifies the "Halt" capability to use /usr/sbin/poweroff in preference
to /usr/sbin/shutdown with parameters, and modifies the associated
test.
- adds an "InsertPublicKey" capability and tests.
- adds a "RemovePublicKey" capability and tests.
With this commit applied, the vast majority of typical Vagrant workflow
is available to SmartOS global zone guests (provided NFS mounts are used
rather than VMWare shared folders).
b84acaed3c