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

lib/here_i_am/devices/device.ex

@@ -4,7 +4,7 @@ defmodule HereIAm.Devices.Device do
 
   schema "devices" do
     field :ip_address, :string
-    field :audio, :string
+    field :tts, :string
 
     timestamps(type: :utc_datetime)
   end
@@ -12,7 +12,7 @@ defmodule HereIAm.Devices.Device do
   @doc false
   def changeset(device, attrs) do
     device
-    |> cast(attrs, [:ip_address, :audio])
-    |> validate_required([:ip_address, :audio])
+    |> cast(attrs, [:ip_address, :tts])
+    |> validate_required([:ip_address, :tts])
   end
 end