fix for PLFM-1662
fixed some tests and added more
fixed tests
Double the fire frequency for the dynamo worker as it is falling behind the data migrator and yet well below DynamoDB throughput
addressed issues raised in the code review
Merge pull request #264 from john-hill/develop

Fix for PLFM-1662
For PLFM-1636, enforce the correct write order
Add test to delete a non-existing object
Unit test better name
Merge pull request #265 from eric-wu/develop

Enforce the correct write order for ancestor-descendant pairs
Image now just contains a filename.  and params now all need to be Strings (to make the md representation easy)
Merge branch 'develop' of https://github.com/Sage-Bionetworks/Synapse-Repository-Services into develop
Merge pull request #267 from jay-hodgson/develop

SWC-357
Improved schema descriptions in Submission.json