Fixing the parsing of the produced XML in bamboo

Please consider this pull request. I have bamboo running a django test bed with the unittest-xml-reporting test runner.

However these error are thrown from the java framework (OSX build agent):

```
2014-11-08 21:01:18,945 ERROR [pool-139-thread-6] [TestCollationServiceImpl] Failed to parse test result file "/Users/bambooagent/bamboo-agent-home/xml-data/build-dir/SW-DCD1-JOB1/src/TEST-code_doc.tests.test_project_revision.ProjectRevis
ionsTest-20141108200109.xml"
org.xml.sax.SAXParseException: Invalid encoding name "utf8".
        at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
        at com.atlassian.bamboo.build.test.junit.JunitTestResultsParser.parse(JunitTestResultsParser.java:90)
        at com.atlassian.bamboo.build.test.junit.JunitTestReportCollector.collect(JunitTestReportCollector.java:40)
        at com.atlassian.bamboo.build.test.TestCollationServiceImpl$1$1.run(TestCollationServiceImpl.java:136)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
        at java.lang.Thread.run(Thread.java:695)
```

The simple fix of the pull request completely solves the issue.

Best,
Raffi