EmptyBlock: can't get violation from case token
Taken from https://github.com/checkstyle/checkstyle/issues/3748#issuecomment-279396341

````
$ cat TestClass.java
public class TestClass {
    void method(int a) {
                switch (a) {}
                switch (a) {case 1:}
                switch (a) {case 1:{}}
                switch (a) {
                    case 1:
                }
                switch (a) {
                    case 1:
                    {}
                }
                switch (a) {
                    case 1:
{
}
                }
    }
}

$ cat TestConfig.xml
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
          "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
          "http://www.puppycrawl.com/dtds/configuration_1_3.dtd">

<module name="Checker">
    <property name="charset" value="UTF-8"/>

    <module name="TreeWalker">
        <module name="EmptyBlock">
            <property name="tokens" value="LITERAL_CASE"/>
        </module>
    </module>
</module>

$ java -jar checkstyle-7.5.1-all.jar -c TestConfig.xml TestClass.java
Starting audit...
Audit done.
````

http://checkstyle.sourceforge.net/config_blocks.html#EmptyBlock
`LITERAL_CASE` is an allowed token, but I can NOT produce a violation for it.

Our tests for the check makes no reference to cases. https://github.com/checkstyle/checkstyle/blob/master/src/test/java/com/puppycrawl/tools/checkstyle/checks/blocks/EmptyBlockCheckTest.java
Even though blocks are mostly considered curlies, it makes sense that we treat `case` and `default` as blocks since the case is grouping code under it.
I assume a `case` that just contains `break` should still be considered empty.

We need to find the issue with the check and expand all our tests to every acceptable token for the check to verify we have no issues with any other tokens.