Merge pull request #20 from cpoulain/master

Add getppid on Windows.
Add support for worksheet directives
Merge pull request #21 from javierluraschi/WorksheetDirectives

Add support for worksheet directives
Validate file system access by bundle
Resolve merge conflict
Remove unwanted file.
Merge branch 'ValidatePaths' of https://github.com/javierluraschi/codalab-cli into review
Validate access to bundle files
fixed issue #25