Fix migration for unique slugs

[paltman]

the PINAX_BLOG_SLUG_UNIQUE setting when set to True, causes a migration to be generated after install. the migrations that ship with pinax-blog were created with the default settings which is False.

perhaps the migration should be edited to be dynamic based on that setting. that doesn't handle the case where you might want to switch after you have installed but could handle the case where you know what you want from the start.

[jtauber]

@paltman do you think this needs to be done for 16.07?

[paltman]

@jtauber ideally but i'm not sure of how to fix it

[paltman]

@brosner any ideas?

[KatherineMichel]

Is this still relevant? Perhaps can be closed at this point.