make fabfile code cleaner

* remove unused imports
* don't redefin id_generator function
make fabfile pep8 compliant
typo in comments
stop if there is an error in home, proxy or data-system installation
remove task test
Merge pull request #27 from poupotte/feature/stopScript

Stop install script if necessary in home, proxy or data-system installation
add robots.txt file
remove useless files
Merge branch 'master' of github.com:mycozycloud/cozy-setup