Validation

[sargant]

It's a completely naive implementation at the moment, with zero validation.

Some thoughts on what validation could encompass:

• Ensuring athlete IDs conform to /^A[0-9]+$/
• Ensuring athlete name and ICE contact name aren't blank
• Ensuring the ICE contact number is exactly that, a number
• Providing a default value of "None" for medical info if the default is cleared

Also - should validation be done on both client & server, or server only? As the pass is retrieved by redirecting to a different URL, we can render a different page with an error message instead.

[sargant]

Partially implemented by #9 and #11