emails now only send by category
default category set in INI is 'all', which is special-cased
all other emails send only if their category is active

 we can use this turn on and off email types per-event
WIP email previewing
for viewing emails that are supposed to go out when SEND_EMAILS is False
mostly for debugging but could later be refactored into an email 'queue' system
Merge branch 'ftr_email_categories' into ftr_email_previews
email previewing, merged with email category branch
for viewing emails that are supposed to go out when SEND_EMAILS is False
public-facing text updates
fix dumb copy+paste error, this now works.
fix bug where AWS_ACCESS_KEY_ID should have been AWS_ACCESS_KEY
tested and confirmed this works.
Merge pull request #278 from EliAndrewC/ftr_email_previews

email previews + Remindercategories
Merge pull request #277 from EliAndrewC/fix_conf_email_text

public-facing text updates
add link to change your password from the account page (I can never find this link)
add event name and year to certain emails so that it's obvious which event they're talking about.
Merge pull request #292 from EliAndrewC/fix_email_not_having_event

add event name and year to certain emails
run stripe form generation through django
this is so we sanitize inputs automatically, which we should be doing here but weren't
add BADGES_SOLD to stats
fix broken summary page
the exclude= param was removed from affiliates() in uber/utils.py a while back
I removed it from summary.py because it seems like it's the same behavior as before
make index.html use the base template
first WIP pass at selenium testing
 my goal here is to eventually make this get through the attendee-facing preregistration process
 if I can do that, I will sleep a lot better at night having these tests run against production and staging servers
 this obviously needs a ton of work to be useful, but it is a decent start
 I'm probably getting too goofy with my static methods and globals, but we can clean it up later if this sticks.
more .idea stuff
Merge pull request #297 from EliAndrewC/bug_summary_page_busted

fix broken summary page
minor tweaks to unsanitized data fix
per Eli's code review comments