fixed IndexOutOfBoundsException in gherkin java support

This bug manifested itself in cucumber-jvm when running against
  a feature with no steps implemented yet.  It looked like this
  in the maven output:

  Scenario: Say hello                     # cucumber/examples/java/helloworld/helloworld.feature:3
    Given I have a hello app with "Howdy"
    When I ask it to say hi    When I ask it to say hiTests run: 3, Failures: 0, Errors: 2, Skipped: 1, Time elapsed: 0.56 sec <<< FAILURE!
Feature: Hello World  Time elapsed: 0.014 sec  <<< ERROR!
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
	at java.util.ArrayList.rangeCheck(ArrayList.java:604)
	at java.util.ArrayList.get(ArrayList.java:382)
	at gherkin.formatter.PrettyFormatter.indentedLocation(PrettyFormatter.java:142)
	at gherkin.formatter.PrettyFormatter.printStep(PrettyFormatter.java:255)
	at gherkin.formatter.PrettyFormatter.match(PrettyFormatter.java:179)
    ...