* Added docker folder to repo

* Ubuntu based docker file can be build from the repo's root by
   ```
   docker-compose -f docker/docker-compose.yml build
   ```
   * and started by
   ```
   docker-compose -f docker/docker-compose.yml build
   ```
 * Restructured code by packaging the CallMonitoring and SpeexConverting
 * main() runs on startup and then watches for disconnected calls as trigger for running again.
 * Commented main file

libs/message/conversion/__init__.py

@@ -0,0 +1,85 @@
+
+import wave, ctypes
+
+
+### Convert fb speex format to wav ###
+######################################
+"""
+This piece of code is just copied & pasted from https://git.savannah.nongnu.org/cgit/fbvbconv-py.git/tree/fbvbconv.py
+which has kindly managed to convert the messages of the answering machine of fritzboxes from a specially configured Speex format to a wave file. All appreciation to the author(s).
+"""
+
+speexlib = ctypes.cdll.LoadLibrary("libspeex.so.1")
+SPEEX_SET_SAMPLING_RATE = 24
+SPEEX_GET_FRAME_SIZE = 3
+
+class SpeexMode(ctypes.c_void_p):
+    pass
+class Speex(ctypes.c_void_p):
+    pass
+class SpeexBits(ctypes.Structure):
+    _fields_ = [
+        ('chars', ctypes.c_char_p),
+        ('nbBits', ctypes.c_int),
+        ('charPtr', ctypes.c_int),
+        ('bitPtr', ctypes.c_int),
+        ('owner', ctypes.c_int),
+        ('overflow', ctypes.c_int),
+        ('but_size', ctypes.c_int),
+        ('reserved1', ctypes.c_int),
+        ('reserved2', ctypes.c_void_p)
+    ]
+
+speex_lib_get_mode = speexlib.speex_lib_get_mode
+speex_lib_get_mode.restype = SpeexMode
+speex_decoder_init = speexlib.speex_decoder_init
+speex_decoder_init.restype = Speex
+speex_decoder_ctl = speexlib.speex_decoder_ctl
+speex_bits_init = speexlib.speex_bits_init
+speex_bits_read_from = speexlib.speex_bits_read_from
+speex_decode_int = speexlib.speex_decode_int
+speex_bits_remaining = speexlib.speex_bits_remaining
+speex_bits_destroy = speexlib.speex_bits_destroy
+
+
+def speex_convert(inp, outp):
+#    rec = open(inp, 'rb').read()
+    rec = inp.read()
+    wav = wave.open(outp, 'wb')
+    wav.setnchannels(1)
+    wav.setsampwidth(2)
+    wav.setframerate(8000)
+
+    mode = speex_lib_get_mode(0)
+    speex = speex_decoder_init(mode)
+    speex_decoder_ctl(speex, SPEEX_SET_SAMPLING_RATE, ctypes.byref(ctypes.c_int(8000)))
+    bits = SpeexBits()
+    speex_bits_init(ctypes.byref(bits))
+    frame_size = ctypes.c_int()
+    speex_decoder_ctl(speex, SPEEX_GET_FRAME_SIZE, ctypes.byref(frame_size))
+
+    output = ctypes.create_string_buffer(2000)
+    offs = 0
+    while offs < len(rec):
+        nbytes = rec[offs]
+        offs += 1
+        if nbytes != 0x26:
+            continue
+        buf = ctypes.create_string_buffer(rec[offs:offs + nbytes])
+        offs += nbytes
+        speex_bits_read_from(ctypes.byref(bits), buf, ctypes.c_int(nbytes))
+        # this loop looks strange, but its like in roger router and seems to work
+        for i in range(2):
+            rc = speex_decode_int(speex, ctypes.byref(bits), output)
+            if rc == -1:
+                break
+            elif rc == -2:
+                print("Decoding error: corrupted stream?");
+                break
+            if speex_bits_remaining(ctypes.byref(bits)) < 0:
+                print("Decoding overflow: corrupted stream?");
+                break
+        wav.writeframes(output[0:2 * frame_size.value])
+
+    wav.close()
+    speex_bits_destroy(ctypes.byref(bits))