Add a component for picking the time to send a job

Users need to pick a time in the next 24hrs, or send a file immediately.

Rationale for this is a bit lost in time-before-holiday, but generally:

‘Now’ and ‘later’ as the inital choices makes it really clear what
this feature is about conceptually.

The choice of times is absolute, eg ‘1pm’ not ‘in 3 hours’

app/templates/views/trial-mode.html

@@ -9,7 +9,6 @@
 <div class="grid-row">
   <div class="column-two-thirds">
     <h1 class="heading-large">Trial mode</h1>
-
     <p>
       All new accounts on Notify start off in trial mode.
     </p>