Do not push if not configured to do so

Otherwise we're showing error message for something user had not
explicitely ask for (issue #227).

trans/models/subproject.py

@@ -432,7 +432,9 @@ class SubProject(models.Model):
         self.create_translations(request=request)
 
         # Push after possible merge
-        if self.git_needs_push() and self.project.push_on_commit:
+        if (self.git_needs_push()
+                and self.project.push_on_commit
+                and self.can_push()):
             self.do_push(request, force_commit=False, do_update=False)
 
         return ret

trans/models/translation.py

@@ -790,7 +790,9 @@ class Translation(models.Model):
                 self.__git_commit(gitrepo, author, timestamp, sync)
 
         # Push if we should
-        if self.subproject.project.push_on_commit and not skip_push:
+        if (self.subproject.project.push_on_commit
+                and not skip_push
+                and self.can_push()):
             self.subproject.do_push(request, force_commit=False)
 
         return True