Changes to sign-up form

[MyfanwyNixon]

https://mapit.mysociety.org/account/signup/

At the moment there's a field for non-profit making users to describe their project. If they tick 'charity' the same field asks for their charity number; if they don't qualify for a discount we don't ask them anything at all.

• Please can we make the 'please provide details of your project' apply to every sign-up, charity, commercial or not commercial?
• It's currently mandatory for those ticking 'non -commercial' but we could make it non-mandatory for others.
• We'll still need to ask for the charity number for charities
• Also include a tickbox: "We like to write about interesting uses of MapIt on the mySociety blog. Please tick here if you are happy for us to get in touch for this purpose'.

[dracos]

It now always ask for details optionally, and have added tickbox about getting in contact.