Fixing lint complaints, removing unused resources

OpenKeychain/src/main/java/org/sufficientlysecure/keychain/pgp/PgpKeyHelper.java

@@ -104,7 +104,7 @@ public class PgpKeyHelper {
      * @return
      */
     public static String convertFingerprintToHex(byte[] fingerprint) {
-        String hexString = Hex.toHexString(fingerprint).toLowerCase(Locale.US);
+        String hexString = Hex.toHexString(fingerprint).toLowerCase(Locale.ENGLISH);
 
         return hexString;
     }
@@ -133,7 +133,7 @@ public class PgpKeyHelper {
     }
 
     private static String convertKeyIdToHex32bit(long keyId) {
-        String hexString = Long.toHexString(keyId & 0xffffffffL).toLowerCase(Locale.US);
+        String hexString = Long.toHexString(keyId & 0xffffffffL).toLowerCase(Locale.ENGLISH);
         while (hexString.length() < 8) {
             hexString = "0" + hexString;
         }