tests: Add basic integration testing

Add basic integration testing of the hypervisor using a cloud-init to
configure the VM at boot and SSH to control it at runtime.

Initial test just boots the VM up checks some basic resources and
reboots. With a second test that calls into the first to check that
subsequent tests work correctly.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

Cargo.toml

@@ -6,5 +6,14 @@ edition = "2018"
 
 [dependencies]
 clap = "=2.27.1"
-
 vmm = { path = "vmm" }
+
+[dev-dependencies]
+ssh2 = "=0.3.3"
+dirs = "2.0.0"
+
+[features]
+default = []
+
+# Integration tests require a special environment to run in
+integration_tests = []