Create tests (#15)

Created a tests folder which contains pytest and bats tests.
Pytest is used to login and send messages to other accounts.
Bats is used to check the log for debug messages.

This fixes #13.

tests/readme.md

@@ -0,0 +1,25 @@
+# Tests
+
+## Dependencies
+
+* docker
+* docker-compose
+* python 3
+
+## Run tests
+
+Execute [`test.bash`](test.bash).
+
+## Upgrade python packages
+
+The following will install the newest version of packages in requirements.txt.
+
+``` bash
+cat requirements.txt | sed 's/==.*//g' | xargs pip install -U
+```
+
+If updates are available --> update and create new version with:
+
+``` bash
+pip-chill > requirements.txt
+```