Fixed PaginationKeyBit (#146)

* Fixed a bug in PaginationKeyBit, PaginationKeyBit wasn't working, It was giving the same result for different pages.

rest_framework_extensions/key_constructor/bits.py

@@ -169,19 +169,14 @@ class PaginationKeyBit(QueryParamsKeyBit):
         {'page_size': 100, 'page': '1'}
 
     """
-    def get_data(self, **kwargs):
-        kwargs['params'] = []
-        if hasattr(kwargs['view_instance'], 'paginator'):
-            if hasattr(kwargs['view_instance'].paginator, 'page_query_param'):
-                kwargs['params'].append(
-                    kwargs['view_instance'].paginator.page_query_param)
-            if hasattr(kwargs['view_instance'].paginator,
-                       'page_size_query_param'):
-                kwargs['params'].append(
-                    kwargs['view_instance'].paginator.page_size_query_param)
-        return super(PaginationKeyBit, self).get_data(**kwargs)
-
-
+    def get_data(self, params, view_instance, view_method, request, args, kwargs):
+        page_dict = {}
+        if hasattr(view_instance, 'paginate_by'):
+            page_dict = {'page_size': view_instance.paginate_by}
+        page_dict.update({'page': request.GET.get('page', 1)})
+        return page_dict
+
+
 class SqlQueryKeyBitBase(KeyBitBase):
     def _get_queryset_query_string(self, queryset):
         if isinstance(queryset, EmptyQuerySet):