Make some cosmetic tweaks to the form to foil spam accounts

Here are a few things we could do to the main "create an account" form that might discourage automated spam:

• Rename the "reason" field to something that spambots will fill in some other way, like "address" or "zip" or ""
• Add a name field that gets hidden via CSS; if it gets filled in, the request should get rejected.
• Change the example 'reason' from "I wish to report an issue in Tor Browser" to something less likely, like "I wish to report an issue in the TorCtl library."