FEATURE REQUEST - Improve 'conditions' options in Pipeline configuration

[fo_connor]

Currently, the `condition` option for conditionally triggering a step can only look at the changeset of a commit. It would be great to have a condition based on files in the repo, not just changed ones. 

This would do wonders for common shared pipelines configuration to be more modular and/or universal. 

Example: 

pipelines:  
  default:
    - step:
        name: Maven Deploy
        script:
            - mvn deploy    
    - step:        
        name: NPM Install        
        script:            
            - cd $NPM_DIRECTORY
            - npm install
        condition:
            files:
                includePaths:
                  # if any directory has a package.json
                  - "**/package.json"