Event nav + ticket request form

[kigster]

This very large PR includes the following changes:

Completed

• Upgrading gems
• Fixing buttons and links
• Switching Event sub-nav to use tabs instead of buttons
• Adding #after_sign_in_path_for() and #set_redirect_path helpers to ApplicationController
• This allows using login/register partial within the context of the ticket request form
• Redirecting from ticket request form to the home if tickets are not on sale yet
• Fixing add admin/demote admin on events admin edit page
• Fixing the ticket request form to work and submit.

Temporarily

• Removed the payments/stripe JS until we redo the integration

Remaining

Wireing up application mailer to the ticket requests.