Fix dependencies for tasks validator
Fix dependencies for tasks validator

There is no package 'yaml' on pypi. Correct name of it
is PyYAML.
Added versions for requirements.

Change-Id: I1c4e9149760fa37800159f789f1840a73c5a42b2
Related: blueprint granular-deployment-based-on-tasks

zhaochao/fuel-library,stackforge/fuel-library,xarses/fuel-library,stackforge/fuel-library,ddepaoli3/fuel-library-dev,huntxu/fuel-library,huntxu/fuel-library,zhaochao/fuel-library,zhaochao/fuel-library,SmartInfrastructures/fuel-library-dev,ddepaoli3/fuel-library-dev,xarses/fuel-library,eayunstack/fuel-library,ddepaoli3/fuel-library-dev,ddepaoli3/fuel-library-dev,huntxu/fuel-library,eayunstack/fuel-library,stackforge/fuel-library,zhaochao/fuel-library,huntxu/fuel-library,stackforge/fuel-library,ddepaoli3/fuel-library-dev,eayunstack/fuel-library,xarses/fuel-library,eayunstack/fuel-library,SmartInfrastructures/fuel-library-dev,zhaochao/fuel-library,SmartInfrastructures/fuel-library-dev,SmartInfrastructures/fuel-library-dev,xarses/fuel-library,eayunstack/fuel-library,SmartInfrastructures/fuel-library-dev,huntxu/fuel-library