Add ASSETS_MODULES Django setting.

Deprecated the auto-load of a project-level "assets.py", which doesn't work
well with Django 1.4 in particular.

Closes #113.

docs/django/settings.rst

@@ -46,3 +46,17 @@ in your project's global settings.
     using with Jinja 2, using which it should be possible to construct a
     Jinja 2 environment which can parse your templates. For more information,
     see :doc:`jinja2`.
+
+.. _django-setting-modules:
+
+.. data:: ASSETS_MODULES
+    :noindex:
+
+    ``django-assets`` will automatically look for ``assets.py`` files in each
+    application, where you can register your bundles. If you want additional
+    modules to be loaded, you can define this setting. It expects a list of
+    importable modules::
+
+        ASSETS_MODULES = [
+            'myproject.assets'
+        ]

docs/upgrading.rst

@@ -59,6 +59,10 @@ Other changes:
   filter and have not explicitly given it a name, you need to do this now if
   you want to register the filter globally.
 
+- ``django_assets`` no longer tries to load a global ``assets.py`` module (it
+  will still find bundles defined in application-level ``assets.py`` files). If
+  you want to define bundles in other modules, you now need to list those
+  explicitly in the :ref:`ASSETS_MODULES <django-setting-modules>` setting.
 
 In 0.6
 ~~~~~~

src/django_assets/env.py

@@ -201,11 +201,8 @@ def autoload():
         #if options.get('verbosity') > 1:
         #    print "assets module loaded"
 
-    # Look for an assets.py at the project level
-    try:
-        import_module('assets')
-    except ImportError:
-        # not found, just ignore
-        pass
+    # Load additional modules.
+    for module in getattr(settings, 'ASSETS_MODULES', []):
+        import_module("%s" % module)
 
     _ASSETS_LOADED = True