[STORM-194] Support list of strings in *.worker.childopts, handle spaces

* Improves argument preparation for ProcessBuilder
* UI decodes topo ids in case some charactors were url-encoded 
* worker.childopts and topology.worker.childopts accept a list of strings (for values that have spaces) or a string (for compatibility with current configs)
* Using conjure for mocking in tests

https://issues.apache.org/jira/browse/STORM-194

Supersedes #17