tests: connection refactor.
add back error handling.
Merge pull request #148 from stephenplusplus/connection-tests

tests: connection refactor.
datastore/request: add API error handling
datastore/request: handle API response with util.handleResp
common/util: lint
datastore/dataset: fix docstring for runInTransaction
Merge pull request #155 from proppy/fix-doc

datastore/dataset: fix docstring for runInTransaction
datastore/request: remove useless return
common/util/handleResp: only add body when non null
Merge pull request #153 from proppy/add-error-handling

datastore/request: add API error handling
Use Connection.requester and rename req to request for clarity