Rule examples doesn't work in Kotlin

[FireZenk]

As specified, the way to define rules in our tests is:

@Rule
public BaristaRule<MyActivity> baristaRule = BaristaRule.create(MyActivity.class);

But translated to Kotlin, we'll get:

@Rule
var baristaRule = BaristaRule.create(MyActivity::class.java)

This will throw an exception like: The @Rule 'baristaRule' must be public

The way to correctly define the Rule in Kotlin is:

@get:Rule
var baristaRule = BaristaRule.create(MyActivity::class.java)

So, maybe will be good to add this divergence somewhere

[rocboronat]

#221 is a proposal to fix this issue 🎉 🍌