[CHORE] ignoring config database and logfile

  * Added lib/data/database.example.json to be copied to lib/data/database.json when configuring the env.
  * Fixed Gruntfile.js syntax error.
Merge pull request #146 from maxiperezc/onboarding-fixes

[CHORE] ignoring database.json and logfile
[FIX] gitignore config.json
Add robust logging with Winston

* Added winston npm module
* Added a transport file at ./logs/[environment].log (default is production)
* Changed console.log to logger.[info:error] in each case
Merge pull request #147 from maxiperezc/add-winston

[Logging] Add robust logging with Winston
[TEST] Test drive correct retryFailedPayment implementation.
[TASK] Bump ripple-rest-client dependency patch version.