Update shell.rst typo

There was a typo. 
"start" was mistyped as "star"
Merge pull request #820 from lisimia/patch-1

Update shell.rst typo
move tests under root dir
move tests requirements under tests dir
use pytest.ini to enable twisted plugin
fix Twisted package name
Fix bench command
remove obsolete shell scripts used to run tests suite
update tox usage on contributing.rst
fix requirements.txt for tests under precise
Merge pull request #827 from dangra/tests-on-root

Move Test cases under project root dir
The sum up of travis-ci builds are taking like 50min to complete
Collect the list of packages not working on python3
Merge pull request #830 from dangra/py3-tests

[WIP] Prevent Python 3 port regressions
added required option to settings module, also documentation