SpeechSynthesisTest: Add tests for Voice.toString.

android/eSpeakTests/src/com/reecedunn/espeak/test/SpeechSynthesisTest.java

         assertThat(voice.locale.getCountry(), is(country));
         assertThat(voice.locale.getISO3Country(), is(iso3Country));
         assertThat(voice.locale.getVariant(), is(variant));
+        assertThat(voice.toString(), is(name));
     }
 
     public void testConstruction()