Add sanity test based on injected data.

[jason-fox]

This PR is similar to ging/fiware-idm#69

• Adds an ECMA6 code linter (run using npm run lint)
• Ensures that the linter runs prior to commit
• Runs the linter as part of the CI Build
• Instantiates a Populated MySQL database for use with the Unit tests.
• Runs code coverage as part of the CI Build (TSC should requirement)
  (the after_script in travis)
• Adds a single unit test stub
  (no body to the tests)

[jason-fox]

Tests can be run locally with the following preparatory steps:

docker network create --driver=bridge my-network
docker run -d -h mysql -p 3306:3306 --net=my-network --name mysql -v $(pwd)/test/mysql-data:/docker-entrypoint-initdb.d/:ro -e MYSQL_ROOT_PASSWORD=test  mysql:5.7

docker pull fiware/idm:latest
docker run -d --net=my-network --name keyrock -p 3000:3000 -e IDM_DB_USER=root -e IDM_DB_PASS=test -e DATABASE_HOST=mysql -e IDM_DB_PORT=3306  fiware/idm:7.5.1 

npm test or npm run test:coverage works thereafter.

The sanity test has been altered to use a local Keyrock instance rather than relying on an existing Keystone on the net. Also incorporates parts of PR #73 which also ran the linter.

The same config.js change is necessary to get the PEP Proxy to run as in the Keyrock test.

The repo needs to be exposed on coveralls as well (obviously) - see https://coveralls.io/repos/new - this is the reason for the error message in the log:

{"message":"Couldn't find a repository matching this job.","error":true}

and the coverage:unknown badge

[apozohue10]

Merged! Thanks! We will work now on travis CI and code coverage.