make "npm run e2e" work again

[talkol]

cd detox/detox
npm install
npm run build
npm run test-clean
npm run test-install
# don't run this now: npm run test
cd test
npm run e2e

The last line is how end users (not people developing detox itself) will eventually run detox
this means any parameters you want to send need to be designed to make sense there, like:
npm run e2e -- --scheme=ios-simulator.release
npm run e2e -- --verbose

If you want to improve the scripts for people developing detox, this must come as step 2 after the API for end users is finished and working

[LeoNatan]

It just works©. npm run e2e is how we run tests on Travis CI.

Other improvements such as verbose, target and scheme should all come when CLI tools are developed (#56).