truncate command output in ps by default

when the PS command was reworked for performance and formatting improvements,
i forgot to truncate the command field.  Long container commands was throwing
the formatting off. we now truncated to 17 characters plus the elipses.

Signed-off-by: baude <bbaude@redhat.com>

cmd/podman/shared/container.go

@@ -24,6 +24,7 @@ import (
 const (
 	cidTruncLength = 12
 	podTruncLength = 12
+	cmdTruncLength = 17
 )
 
 // PsOptions describes the struct being formed for ps
@@ -191,9 +192,12 @@ func NewBatchContainer(ctr *libpod.Container, opts PsOptions) (PsContainerOutput
 	pod := ctr.PodID()
 	if !opts.NoTrunc {
 		cid = cid[0:cidTruncLength]
-		if len(pod) > 12 {
+		if len(pod) > podTruncLength {
 			pod = pod[0:podTruncLength]
 		}
+		if len(command) > cmdTruncLength {
+			command = command[0:cmdTruncLength] + "..."
+		}
 	}
 
 	pso.ID = cid