Fix miscellaneous docstring issues.

Currently building the docs shows:
```
/vumi-jssandbox-toolkit/docs/app.rst:11: WARNING: Field list ends without a blank line; unexpected unindent.
/vumi-jssandbox-toolkit/docs/app.rst:91: WARNING: Block quote ends without a blank line; unexpected unindent.
/vumi-jssandbox-toolkit/docs/states.rst:7: WARNING: Field list ends without a blank line; unexpected unindent.
/vumi-jssandbox-toolkit/docs/tester.rst:26: WARNING: Inline interpreted text or phrase reference start-string without end-string.
/vumi-jssandbox-toolkit/docs/tester.rst:92: WARNING: Bullet list ends without a blank line; unexpected unindent.
/vumi-jssandbox-toolkit/docs/tester.rst:96: WARNING: Bullet list ends without a blank line; unexpected unindent.
/vumi-jssandbox-toolkit/docs/tester.rst:99: WARNING: Bullet list ends without a blank line; unexpected unindent.
/vumi-jssandbox-toolkit/docs/user.rst:126: WARNING: duplicate object description of setup, other instance in /vumi-jssandbox-toolkit/docs/states.rst
```