improve the DateFormatterTest

[muellerc]

I improved the DateFormatter test to work in other TimeZones too (not only in my one ;-) ).

[TomasMorecom]

Have anyone fixed the broken DateFormatterTest yet? I tried to apply this patch, and it resolved one of the tests but still I get this
Expected: 130101050000000R
Actual: 121231170000000R
:
formatRelativeDate(org.jsmpp.util.DateFormatterTest) Time elapsed: 0.006 sec <<< FAILURE!
java.lang.AssertionError: expected: <13010105000000R> but was: <121231170000000R>
at org.testng.Assert.fail(Assert.java:89)
at org.testng.Assert.failNotEquals(Assert.java:480)
at org.testng.Assert.assertEquals(Assert.java:118)
at org.testng.Assert.assertEquals(Assert.java:171)
at org.testng.Assert.assertEquals(Assert.java:181)
at org.jsmpp.util.DateFormatterTest.formatRelativeDate(DateFormatterTest.java:129)

[dpocock]

I've opened a new issue for this opentelecoms-org/jsmpp#1

As described there, both the RelativeTimeFormatter and the unit test appear to be wrong.

[dpocock]

Merged here: opentelecoms-org/jsmpp@50ff268