Flesh out multi-user in am commands.

Now we default to the current user instead of user 0 for most commands
(except where we can do the command for all users).

Many more commands take a user argument: force-stop, kill, profile,
dumpheap.

Improved help text.

Change-Id: I719a13b4d31b668f57ca21e51d7043ac3e0d4e1b
diff --git a/services/java/com/android/server/pm/UserManagerService.java b/services/java/com/android/server/pm/UserManagerService.java
index a13c16e..3391668 100644
--- a/services/java/com/android/server/pm/UserManagerService.java
+++ b/services/java/com/android/server/pm/UserManagerService.java
@@ -281,7 +281,7 @@
      * cache it elsewhere.
      * @return the array of user ids.
      */
-    int[] getUserIds() {
+    public int[] getUserIds() {
         synchronized (mPackagesLock) {
             return mUserIds;
         }