Restore JUnit assert checkstyle restrictions

[philwebb]

We've lost

<module name="com.puppycrawl.tools.checkstyle.checks.regexp.RegexpSinglelineJavaCheck">
	<property name="maximum" value="0"/>
	<property name="format" value="org\.junit\.Assert\.assert" />
	<property name="message"
		value="Please use AssertJ imports." />
	<property name="ignoreComments" value="true" />
</module>

somehow