End to End Test Case for APIs

[iamsamirzon]

Summary
Automated Test Cases to be executed before every release for all APIs
Intended Outcome
A test suite is created over time and added iteratively over the lifetime of this project development
Additional context
The unit testing will be included in RC-1. The community met on 5/26 and made the decision to split this work as unit and end to end testing.

[dtzar]

Migrated to notaryproject/notation-go#52

[yizha1]

This is actually API testing and was closed by notation-go refactoring, which is duplicated with notaryproject/notation-go#52