Add integration test for server package

tests/inputs/server_config.json

@@ -1,6 +1,5 @@
 {
-    "tts_path":"TTS/tests/outputs/",  // tts model root folder
-    "tts_file":"checkpoint_10.pth.tar",     // tts checkpoint file
+    "tts_checkpoint":"checkpoint_10.pth.tar",     // tts checkpoint file
     "tts_config":"dummy_model_config.json",     // tts config.json file
     "tts_speakers": null,           // json file listing speaker ids. null if no speaker embedding.
     "wavernn_lib_path": null,   // Rootpath to wavernn project folder to be imported. If this is null, model uses GL for speech synthesis.