Allow apps to extend/wire custom module tests

[anilcse]

Currently, the QA integration scripts allows one to test cosmos-sdk functionality with any application. But it doesn't allow app developers to integrate their custom modules cleanly. Now either they should fork and build their own modules or write custom scripts to test both sdk functionality and their own app specific modules.

Solution:

• Create a simple script and make file definition to allow app developers to use QA scripts and wire their scripts for testing end-to-end. Something like

make test-all should call a script internally, which will execute all the sdk tests and app specific tests.