Remove redundant STATICFILES_DIRS setting

If STATICFILES_FINDERS contains the AppDirectoriesFinder, which by
default it does, there is no need to specify ../aira/static in
STATICFILES_DIRS, because it will look in there by itself anyway.
Simplify TEMPLATE_DIRS setting

If TEMPLATE_LOADERS contains app_directories.Loader, which by default it
does, there is no need to specify aira/templates in TEMPLATE_DIRS,
because it will look in there by itself anyway. The whole TEMPLATE_DIRS
setting has been removed, together with a little bit of template file
relocating.