Travis: truffle migration fails

[srya-b]

The most recent pull request of the incentive layer fails on Travis. On closer inspection of the output, the test fails when running:

> npm run migrate

This command just runs truffle migrate --reset. Locally run, the truffle command works correctly without a failure. When `npm run migrate`` is run, then failures happen sometimes.

This suggests that there is a race condition somewhere in the migration process.