switch mp3 to tts, add genserver to app supervisor tree that periodically checks for newly connected devices and plays their associated tts message

config/test.exs

@@ -11,7 +11,8 @@ config :here_i_am, HereIAm.Repo,
   hostname: "localhost",
   database: "here_i_am_test#{System.get_env("MIX_TEST_PARTITION")}",
   pool: Ecto.Adapters.SQL.Sandbox,
-  pool_size: System.schedulers_online() * 2
+  pool_size: System.schedulers_online() * 2,
+  port: 5560
 
 # We don't run a server during test. If one is required,
 # you can enable the server option below.