Merge branch 'stable'

Coverage and dependency badges
Introduce mode variable to change endpoint configuration for all endpoints. Remaining config kept as they are
Update with mode
update with mode
doc that redirect uri is required
Enable developers easy access to debug id when NODE_ENV is set to development
Improve docs for how error handling happens in sdk, and access to debug id
Allow tests to be run in mock mode by default and NOCK_OFF can be set to true to hit sandbox or live
Add mocks for api calls
By default run tests in mock mode, if NOCK_OFF=true is set then run on live or sandbox
Merge branch 'fix_config'

Enable mock mode for unit tests, run those by default.
Reduce configurations by introducing mode variable for config
NODE_ENV can be set to development to access debug id needed when contacting Merchant Services
Merge branch 'master' into stable

Merge in master