Protect against case where user is null.

User field is nullable but some functions don't check for None before trying to access fields
change url priority for SLUG_URLS = False

Previous urls.py priority will cause question page not accessible,
but category page instead, when SLUG_URLS is set to False.
Merge pull request #44 from twoolie/patch-1

Protect against case where user is null.
fix markup loading of markdown. oops.
Merge pull request #45 from tzangms/master

fix urls.py priority
strip first/last name for falsy
bump version
ensure works on latest 1.4.5
add compat with 1.5
Merge pull request #46 from zapier/1.5-compat

add compat with 1.5
Add compatibility with 1.5 configurable user model

Made user `ForeignKey` compatible with Django 1.5. Previous versions still supported.
Merge pull request #47 from artscoop/patch-1

Add compatibility with 1.5 configurable user model
fix settings clobbering
import django settings explicitly
add select related and fix needless queries
bump version
mergin'!