optimize execution-scripts

[chrishelgert]

optimizing the recursive install and test-script with using es6-generators.

changes

• child_process.spawn instead of execSync
• promise-wrapper around spawn
• iteration over projects with es6-generator

what does it bring us:

• execSync gives feedback when the execute is finished
• spawn gives feedback on the fly

[chrishelgert]

it also fixes a bug in install-script. npm writes WARN in stderr which brokes the install-script