Fix secret EditText display and other fixes.

+ Now it shows shadowed "(unchanged)" (as in wifi settings) and "(not set)"
  instead of two dots.

Patch Set 2:
+ Show cancellation confirmation dialog only when there's change in
  profile.

Patch Set 3:
+ Re-enable profile preferences when the reconnect dialog is cancelled.
diff --git a/res/values/strings.xml b/res/values/strings.xml
index f63a0a6..b96f3ee 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -1829,7 +1829,7 @@
     <string name="vpn_yes_button">Yes</string>
     <string name="vpn_no_button">No</string>
     <string name="vpn_back_button">Back</string>
-    <string name="vpn_mistake_button">No, it's a mistake</string>
+    <string name="vpn_mistake_button">No</string>
 
     <string name="vpn_menu_done">Save</string>
     <string name="vpn_menu_cancel">Cancel</string>
@@ -1935,6 +1935,10 @@
     <string name="vpn_settings_title">VPN settings</string>
     <!-- Summary of preference to enter the VPN settings activity -->
     <string name="vpn_settings_summary">Set up &amp; manage Virtual Private Networks (VPNs)</string>
+    <!-- A secret edit field's grayed out value when it has not been modified -->
+    <string name="vpn_secret_unchanged">(unchanged)</string>
+    <!-- A secret edit field's grayed out value when it has not been set -->
+    <string name="vpn_secret_not_set">(not set)</string>
 
     <!-- Title of preference group for credential storage settings -->
     <string name="cstor_settings_category">Credential storage</string>