Add synapse unit testing framework

[sajithaliyanage]

Provide a built-in way to execute a unit test against a given synapse configuration artifact such as sequence, proxy, api, local entry, endpoint.

Following tasks will be added from this PR,

• Test Proxy services with test cases, input payloads and transport properties
• Test APIs with test cases, input payloads and transport properties
• Test Sequences with test cases, input payloads and synapse, axis2, transport properties
• Undeploye all the deployed configurations
• Customize the starting port of unit testing framework