Prevent potential shell injection by escaping / quoting the command arguments
(directory and file name).
Don't require local or remote action script to be executable and set the execution bit ourselves when uploading the file.
Fix boolean values handling when building local / remote script command line arguments string.

Boolean arguments need to be passed in form of "--<arg>" if the value is True.
Fix typo in the doc.
Add test for parameter to command-line argument conversion.
Merge pull request #765 from StackStorm/fabric_runner_improvements_and_fixes

Fabric runner improvements and fixes