Add AuthenticationActivity.kt

app/src/main/java/chat/rocket/android/app/AuthenticationActivity.kt

+package chat.rocket.android.app
+
+import android.app.Activity
+import android.app.Fragment
+import android.os.Bundle
+import chat.rocket.android.R
+
+/**
+ * @author Filipe de Lima Brito (filipedelimabrito@gmail.com)
+ */
+class AuthenticationActivity : Activity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_authentication)
+
+        addFragment(AuthenticationServerFragment(), "roomListFragment")
+    }
+
+    private fun addFragment(fragment: Fragment, tag: String) {
+        fragmentManager.beginTransaction().add(R.id.fragment_container, fragment, tag).commit()
+    }
+}
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