Update MobileCapabilityType.java

capability to accept accento on keyboard see appium#239

Author: eliasnogueira

src/main/java/io/appium/java_client/remote/MobileCapabilityType.java

@@ -41,4 +41,7 @@ public interface MobileCapabilityType extends CapabilityType {
 
  //Sauce-specific
  String APPIUM_VERSION = "appiumVersion";
+ 
+ // capability to accept accento on keyboard
+ String UNICODE_KEYBOARD = "unicodeKeyboard";
 }