Add Sequence to appropriate columns
Add foreign key constraints
Add mlbam_player table
Add references to new mlbam_player table
Add constraint for balls and strikes

There are other constraints that could be added I think, but this is the
most obvious one. Note that the columns should reflect the count before
the pitch, not after.
Add missing comma
Fix references and column name
Remove vim-specific ignore and make .py? broader
Use the new model
Fix reference to right variable
Remove count constraint

This would be useful to catch bad data, but then verification of the
data when it's bad is needed. I don't have the resources for that.