travis: Update Travis config to install and test all packages.

Author: eeshangarg

.travis.yml

@@ -2,8 +2,11 @@ language: python
 python:
   - "2.7"
 install:
-  - pip install .
-  - bots_api/provision.py
+  - pip install pycodestyle==2.3.1
+  - pip install ./zulip
+  - pip install ./zulip_bots
+  - pip install ./zulip_botserver
 script:
   - tools/lint
-  - bots_api/test-bots
+  - python -m unittest discover -v zulip_botserver
+  - tools/test-bots