Arvados

Minor updates:
- Split the list of parameters returned for a method into required and optional lists to enhance usability.
- Fixed array to json conversion conversion in putParameter method. Previously, this was working only for array of array (filter) case and hence corrected to work with just array objects as well.

1. returning getAvailableParametersForMethod() as a map with just "required" and "optional" seems awkward, how about returning it as an array with two items?
2. getJsonValueFromListType() uses Arrays.deepToString. Is this guaranteed to produce valid JSON?