Allow validator to check format rather than exact string match for some variables

[mwvoss]

Some variables would be unique per study and should be validated for format rather than exact match. So far these include:

"StudyName"
"ChangeinFM" (determine what unit is and whether two variables are needed for raw and percent change respectively)
Possibly "InterventionIntensity" (see Issue #24)

[zkhan12]

Just wanted to touch base on this again @mwvoss, I added a validation check for StudyName based on the format (on dev branch) but I'm not sure what format we are aiming for with the other columns so I held off on those.