action field displays an error in the history list .

[liron-li]

If this is a bug please specify versions you're using first.

Django version: 1.10
Django Suit version: 0.2.25
Python version: 3.6

Issue: action field displays an error in the history list .

like this：

[{"added": {}}]

[darklow]

Please submit more detailed report and description of the problem including full error stacktrace and example code that shows how to replicate error.

[kliyes]

@liron-li check #533

[liron-li]