Changes to make plugin generic to support other unit test frameworks

The said changes makes the plugin generic to any kind of unit test framework. 
Following changes have been as part of the pull request:
- Converted String based data approach to JSON based approach.
- Added support to provide parentId and parentName for tree creation. This is done because not every test frameworks provide details of all the methods to be executed in a test-run at the start of the execution.
- Modified the UI to add nodes using parentId once the tree has been created already.

We are writing new clients to support other unit test frameworks and the said changes will help us in doing so.