Added registry of top-level descriptors
First commit of JSON deserializer
Improved error
and (as a work-around) don't blow but ignore multiple adding of identical items to the ids registry.
Need to figure out why they were added multiple times though.
Merge from cherry-pick branch
Addressed a whitespace comment
Removed workaround
Convert xml test data to JSON and use that for deserialization test instead of a fixture file.
Removed unused method
Addressed comments
Addressed comment by refactoring a little
Merge branch 'develop' into feature/JSON_alps
Merge branch 'develop' into feature/JSON_alps
Addressed comment - moved file rewind to after block
Merge pull request #39 from mdsol/feature/JSON_alps

Feature/json alps