Upgrade to wagtail 2.2 in requirements and tests

setup.py

@@ -2,7 +2,7 @@ import re
 from setuptools import find_packages, setup
 
 install_requires = [
-    'wagtail>=2.0,<2.1',
+    'wagtail>=2.2,<2.3',
     'user-agents>=1.0.1',
     'wagtailfontawesome>=1.1.3',
 ]

tox.ini

@@ -1,12 +1,12 @@
 [tox]
-envlist = py{36}-django{111}-wagtail{20},lint
+envlist = py{36}-django{111}-wagtail{22},lint
 
 [testenv]
 commands = coverage run --parallel -m pytest {posargs}
 extras = test
 deps =
     django111: django>=1.11,<1.12
-    wagtail19: wagtail>=2.0,<2.1
+    wagtail19: wagtail>=2.2,<2.3
 
 [testenv:coverage-report]
 basepython = python3.6