Flexible formatting of DecimalType

My initial pull request #18 threw an exception, if a DecimalType like "11.0" was formatted with an integer pattern like "%d". This pull request contains a fix for this issue.

Details can be found on the original issue of openHab: https://github.com/openhab/openhab/issues/1013


Note: I've also added a fix for the test suite org.eclipse.smarthome.ui.test, which is disabled at the moment (I think because of localization issues with the decimal separator). I fixed this localization issue but I get an error (Surefire cannot find the bundle) when I try to activate the test suite. In openHab I could activate this test suite without problems.

To point it out: The test suite should work with my fixes, but the whole test suite does not execute because of an Surefire error, as soon as I active the tests in pom.xml:

```
!ENTRY org.eclipse.osgi 4 0 2014-06-02 11:34:12.637
!MESSAGE Application error
!STACK 1
java.lang.RuntimeException: Bundle org.eclipse.smarthome.ui.test is not found
	at org.eclipse.tycho.surefire.osgibooter.OsgiSurefireBooter.getBundleClassLoader(OsgiSurefireBooter.java:149)
	at org.eclipse.tycho.surefire.osgibooter.OsgiSurefireBooter.run(OsgiSurefireBooter.java:67)
	at org.eclipse.tycho.surefire.osgibooter.HeadlessTestApplication.run(HeadlessTestApplication.java:21)
```

Any hints about what is going wrong here? And how I could fix this bundle problem?