Feature/integration testing

[markglh]

Adds automated integration testing to the library, running tests against a dockerized (localstack) Kinesis instance.

• Update to use https://hub.docker.com/r/markglh/initialised-localstack/ instead of the local Dockerfile.
• Implement Producer Integration Test
• Create test producer/consumer to aid testing
• Run integration tests in travis

Addresses:
#20
#21

Follow up issue: #38

[coveralls]

Coverage remained the same at 86.777% when pulling a104e12 on feature/IntegrationTesting into 5bff161 on master.

[coveralls]

Coverage remained the same at 86.777% when pulling bc4ea0d on feature/IntegrationTesting into 5bff161 on master.

[coveralls]

Coverage remained the same at 86.777% when pulling bc4ea0d on feature/IntegrationTesting into 5bff161 on master.

[coveralls]

Coverage decreased (-0.6%) to 86.226% when pulling 04d9384 on feature/IntegrationTesting into 5bff161 on master.

[coveralls]

Coverage remained the same at 86.777% when pulling f8e8166 on feature/IntegrationTesting into 5bff161 on master.

[coveralls]

Coverage remained the same at 86.777% when pulling fb393b2 on feature/IntegrationTesting into 5bff161 on master.

[coveralls]

Coverage remained the same at 86.777% when pulling 47275c6 on feature/IntegrationTesting into 5bff161 on master.

[coveralls]

Coverage remained the same at 86.777% when pulling 47275c6 on feature/IntegrationTesting into 5bff161 on master.