Setup custom routers before settings up signal processor.

Fixes https://github.com/toastdriven/django-haystack/issues/727
Merge pull request #731 from adityar7/master

Setup custom routers before settings up signal processor.
update_index: display Unicode model names (closes #767)

The model's verbose_name_plural value is included as Unicode but under
Python 2.x the progress message it was included in was a regular
byte-string. Now it's correctly handled as Unicode throughout.