authentication: Fixed HTTPS prefixed URL normalization.

I'm assuming here that the if statement is supposed to be checking whether the normalized URL starts with HTTP or HTTPS. The current version seemingly has a typo which this commit fixes.

src/main/java/com/owncloud/android/authentication/AuthenticatorUrlUtils.java

@@ -78,7 +78,7 @@ public abstract class AuthenticatorUrlUtils {
             normalizedUrl = normalizedUrl.trim();
 
             if (!normalizedUrl.toLowerCase(Locale.ROOT).startsWith(HTTP_PROTOCOL) &&
-                    !normalizedUrl.toLowerCase(Locale.ROOT).startsWith(HTTP_PROTOCOL)) {
+                    !normalizedUrl.toLowerCase(Locale.ROOT).startsWith(HTTPS_PROTOCOL)) {
                 if (sslWhenUnprefixed) {
                     normalizedUrl = HTTPS_PROTOCOL + normalizedUrl;
                 } else {