added subscription status to templates

[jtauber]

this provides a template snippet that shows subscription status such as:

• "Your subscription has been canceled."
• "Your subscription has been canceled but you can continue to use the site for another 1 day, 12 hours."
• "Your free trial will end in 6 days, 13 hours after which you will need to get a subscription to continue using the site."
• "Your free trial will end in 2 days, 8 hours after which you commence a Habitualist Monthly ($5/month) plan."

This snippet has been added to subscribe, change card, change plan and history templates.

[jtauber]

The snippet can also be used anywhere else on the site, of course.