fixed i18n for sqla filters

flask_admin/contrib/sqla/filters.py

 import warnings
 
-from flask.ext.admin.babel import gettext
+from flask.ext.admin.babel import lazy_gettext
 from flask.ext.admin.model import filters
 from flask.ext.admin.contrib.sqla import tools
 
@@ -33,7 +33,7 @@ class FilterEqual(BaseSQLAFilter):
         return query.filter(self.column == value)
 
     def operation(self):
-        return gettext('equals')
+        return lazy_gettext('equals')
 
 
 class FilterNotEqual(BaseSQLAFilter):
@@ -41,7 +41,7 @@ class FilterNotEqual(BaseSQLAFilter):
         return query.filter(self.column != value)
 
     def operation(self):
-        return gettext('not equal')
+        return lazy_gettext('not equal')
 
 
 class FilterLike(BaseSQLAFilter):
@@ -50,7 +50,7 @@ class FilterLike(BaseSQLAFilter):
         return query.filter(self.column.ilike(stmt))
 
     def operation(self):
-        return gettext('contains')
+        return lazy_gettext('contains')
 
 
 class FilterNotLike(BaseSQLAFilter):
@@ -59,7 +59,7 @@ class FilterNotLike(BaseSQLAFilter):
         return query.filter(~self.column.ilike(stmt))
 
     def operation(self):
-        return gettext('not contains')
+        return lazy_gettext('not contains')
 
 
 class FilterGreater(BaseSQLAFilter):
@@ -67,7 +67,7 @@ class FilterGreater(BaseSQLAFilter):
         return query.filter(self.column > value)
 
     def operation(self):
-        return gettext('greater than')
+        return lazy_gettext('greater than')
 
 
 class FilterSmaller(BaseSQLAFilter):
@@ -75,7 +75,7 @@ class FilterSmaller(BaseSQLAFilter):
         return query.filter(self.column < value)
 
     def operation(self):
-        return gettext('smaller than')
+        return lazy_gettext('smaller than')
 
 
 # Customized type filters