merge jbossts-common into jbossjta.jar/jbossjts.jar

As no other project consumes jbossts-common as an independent entity, it makes little sense to preserve it as such. For ease of embedding we should have all the files in a single .jar. Remove jbossts-common.jar and merge the contents into jbossjta.jar or jbossjts.jar according to distribution type.