[TASK] set issuer on destination_amount attribute in ripple-rest

Regarding iterating each property vs asserting the entire stringified response body, I think there are a few key advantages to keeping it as asserting each property

1. It's easy to tell what broke reading the test output from the command line because each test tests a particular part of the system
2. Based on 1, it becomes easy to locate the offending code and fix it

Concerning the question of efficiency, I recognize that this approach potentially introduces additional complexity in the form of lines and processing but my argument for this is that expressiveness in a test can be viewed at a higher priority than efficiency because it's not a performance sensitive client facing application. That said, we shouldn't strive to write O(e^n) either.

If it's a concern of test coverage/sanity checking, I'd be happy to write more tests that cover the holes that these tests missed out on.