Validation of Subject Metadata

[jmdelahanty]

Since I'm a bad programmer and haven't tried to make a GUI that properly records surgical/subject metadata, its very easy to accidentally mistype yaml spacing by hand.

A new branch for validating subject metadata has been created that currently just iterates through all the subjects of a given input project name. This should be made a lot nicer and realistically an exception for this specific kind of failure should be made.