Extend hello nf-core to include parameter validation

[adamrtalbot]

The new hello nf-core series does not include modifying any parameters or setting the schema, however when you are updating the test profile there is an obvious place to put it:

        // Input data
        input  = 'core-hello/assets/greetings.csv'

        // Other parameters
        batch     = 'test'
        character = 'tux'

We can update the parameters for the:

• batch
• character
• remove the input schema

[vdauwera]

I believe this will be addressed by #672