Need to handle running server/port conflict

[yeekangc]

gradle build -i (as per the guide) failed.

Failure was with the integration test:
io.openliberty.guides.hello.it.EndpointIT > testServlet FAILED
java.lang.AssertionError: HTTP GET failed expected:<200> but was:<404>
at org.junit.Assert.fail(Assert.java:88)
at org.junit.Assert.failNotEquals(Assert.java:834)
at org.junit.Assert.assertEquals(Assert.java:645)
at io.openliberty.guides.hello.it.EndpointIT.testServlet(EndpointIT.java:42)

This was due to an already running Liberty server from working with another guide. The guides need to handle such situation better.