fixed minimum version requirements and tidied dockerfile

Dockerfile

@@ -1,5 +1,11 @@
 FROM python:3.5-alpine
+
+# copy files
 WORKDIR /maki
 COPY ["requirements.txt", "*.py", "./"]
+
+# install dependencies
 RUN pip install -r requirements.txt
+
+# start bot
 CMD ["python", "./bot.py"]

requirements.txt

@@ -1,2 +1,3 @@
-discord.py==0.15.1
+discord.py>=0.16.0
 requests>=2.20.0
+ftfy>=5.5.0