[Broker-J] broker-core unit tests are failing because of wrong locale

The tests make assumptions that they are running in a Locale where the comma character is used to separate thousands in long numbers, and the dot character is used to separate whole numbers from decimal fractions.

There are two types of errors, one where numbers are formatted in the tests using the default Locale, but compared to output from the Broker messages which always use Locale.US. Secondly there are tests which assume the output value from the Broker will always be in a Locale.US format, but are actually determined by the current Locale inside the broker (e.g. in the HTTP management API, and in storing JSON).