Refactored DB query methods

- Removed duplicated logic from methods, factored out into dbQuery
method
- Improved readability of SQL by splitting it onto multiple lines
Renaming variables

- tweet is now tweetActivity as it's an instance of a Gnip tweet
activity information
- hasGeo is now geoInBoundingBox and hasGeo signifies if geo coordinates
were present
Dependency updates

- Updating readme to reflect depencies
Prevent DB constraint violations

- By checking if a unique user exists before we try and insert it again
- Also factored out 'does user exist' method
DB method refactoring

- Fixing issues with return values
- Improving logging
- Improving JSDoc
DB callback error handling

- Catch exceptions in the success handler which were being silently
discarded
DB connection check

- Check that DB is available at startup
Adding TODO for SQL escaping
Merge branch 'master' of https://github.com/smart-facility/cognicity-reports-powertrack

Conflicts:
	README.md