Address PR feedback

- Use fixed dependency versions
- Switch from Jest to Mocha + Chai to be closer to Truffle test setup
- Remove unused tools/deploy_token_genesis.js
- Split off Contract#_ensureStateOneOf from Contract#_ensureState
- Refactor deployment_tool into multiple files
- Add `npm run test:deployment_tool` and hook into travis
- Add README to tools directory, explaining the usage of the deployment tool lib

.travis.yml

@@ -25,5 +25,6 @@ before_script:
   - npm run compile
 script:
   - npm run test
+  - npm run test:deployment_tool
 after_script:
   - kill $(ps aux | grep 'ganache-cli' | awk '{print $2}')