Plan validation:
1. Each phase must be defined within phase document bundle.
2. Each phase does not return error for Validate method
Phase validation:
1. Document bundle associated with the phase can be rendered without an
error.
2. Associated executor must not return an error.
Relates-to: #330
Change-Id: I08c5e8e42570f2cafdced5a02481b033414ffae0
f0e276bb7b