Unification of test data

[CMCDragonkai]

Each client package are using their own set of data for unit test, this
may lead to inconsistency among different client packages. One of the
approaches to resolve such inconsistency is to unify the data (i.e.
sample HTTP requests / responses) used in unit tests and isolate these
data from the test suite of each individual client package.

The Python client places the majority of test data in separate json
files, this is a viable solution to test data isolation.