Merge pull request #15 from soul2zimate/master

Take care potential IOException, at least printStackTrace
don't add null value to bug list if XmlRpcException occurs.
Merge pull request #16 from soul2zimate/master

don't add null value to bug list if XmlRpcException occurs
Merge pull request #17 from soul2zimate/master

don't add null value to bug list if XmlRpcException occurs.
refactor/cleanup Bugzilla.java and add a new RepositoryService for getting branches.