Add bootstrap command to scafold an empty livetest project

[sebastianneubert]

As an user of livetest, I want to use a simple bootstrap command to scafold an empty livetest configuration and an empty testsuite

$ livetest bootstrap
 Creating a new livetest project? [Y/n]  Y
 - creating folders for tests ... [OK]
 - creating empty configuration file conf.yml ... [OK]
 - creating empty testsuite testsuite.yml [OK]
COMPLETE
please run your livetest suite with "livetest run testsuite.yml config.yml"
$