Validate Player Number

Need to disable Bid button upon validation errors and display error
tooltip.

Fixed Team binding problem by essentially abusing a global static
variable. I'm disappointed but some things simply cannot be done in WPF
owing to its complexity. I could write a multi-side document about all
the things playing against me in this particular case.

I can't bind to a newly created datacontext because IoC is creating my
instance, I can't get hold of the source I need to bind the current team
to a dependency property I created on the validation rule. Meh. Global
statics it is. It's after 01:00.