Installer: Handle VM uninstall before it has had a time to boot

Change-Id: I615bc949b5054b301899b1e0b7eae94a98126e61
diff --git a/core/installer/vpn.go b/core/installer/vpn.go
index beeb8e4..0176383 100644
--- a/core/installer/vpn.go
+++ b/core/installer/vpn.go
@@ -65,10 +65,11 @@
 	if err != nil {
 		return err
 	}
-	if resp.StatusCode != http.StatusOK {
-		var buf bytes.Buffer
-		io.Copy(&buf, resp.Body)
-		return errors.New(buf.String())
+	if resp.StatusCode == http.StatusOK {
+		return nil
+	}
+	if resp.StatusCode == http.StatusNotFound {
+		return ErrorNotFound
 	}
 	return nil
 }
@@ -82,10 +83,11 @@
 	if err != nil {
 		return err
 	}
-	if resp.StatusCode != http.StatusOK {
-		var buf bytes.Buffer
-		io.Copy(&buf, resp.Body)
-		return errors.New(buf.String())
+	if resp.StatusCode == http.StatusOK {
+		return nil
+	}
+	if resp.StatusCode == http.StatusNotFound {
+		return ErrorNotFound
 	}
 	return nil
 }
@@ -103,10 +105,11 @@
 	if err != nil {
 		return err
 	}
-	if resp.StatusCode != http.StatusOK {
-		var buf bytes.Buffer
-		io.Copy(&buf, resp.Body)
-		return errors.New(buf.String())
+	if resp.StatusCode == http.StatusOK {
+		return nil
+	}
+	if resp.StatusCode == http.StatusNotFound {
+		return ErrorNotFound
 	}
 	return nil
 }