enable gocritic linter

The linter ensures a common code style.
- use switch/case instead of else if
- use if instead of switch/case for single case statement
- add space between comment and text
- detect the use of defer with os.Exit()
- use short form var += "..." instead of var = var + "..."
- detect problems with append()
```
newSlice := append(orgSlice, val)
```
  This could lead to nasty bugs because the orgSlice will be changed in
  place if it has enough capacity too hold the new elements. Thus we
  newSlice might not be a copy.

Of course most of the changes are just cosmetic and do not cause any
logic errors but I think it is a good idea to enforce a common style.
This should help maintainability.

Signed-off-by: Paul Holzinger <pholzing@redhat.com>

test/e2e/pod_initcontainers_test.go

@@ -114,7 +114,7 @@ var _ = Describe("Podman init containers", func() {
 		check := podmanTest.Podman([]string{"container", "exists", initContainerID})
 		check.WaitWithDefaultTimeout()
 		// Container was rm'd
-		//Expect(check).Should(Exit(1))
+		// Expect(check).Should(Exit(1))
 		Expect(check.ExitCode()).To(Equal(1), "I dont understand why the other way does not work")
 		// Lets double check with a stop and start
 		stopPod := podmanTest.Podman([]string{"pod", "stop", "foobar"})