facenet.pb instead of optimized_facenet.pb in PreferencesHelper.java

[thecurious1-sudo]

I think in your PreferencesHelper.java file, the "facenet.pb" should be replaced with "optimized_facenet.pb" as there is no file named facenet.pb

public String getTensorFlowModelFile(){
        return sharedPreferences.getString("key_modelFileTensorFlow", "facenet.pb");
    }

should be

public String getTensorFlowModelFile(){
        return sharedPreferences.getString("key_modelFileTensorFlow", "optimized_facenet.pb");
    }