Removal of unmaintained dependencies

[YasharF]

gulp-coveralls is no longer being maintained
#46 is moving sinon-mongoose's dependency to a maintained fork, but in the long run, it might be worth looking into an alternative that is better maintained or perhaps remove the dependency altogether.

isparta is no longer being maintained
The repo is marked with the badge http://unmaintained.tech
For code quality and to reduce npm audit issues I would recommend either to just remove the dependency or find an alternative

gulp-istanbul / istanbul is no longer being maintained
istanbul's deprecation message: "This module is no longer maintained, try this instead: npm i nyc Visit https://istanbul.js.org/integrations for other alternatives." -- source: npm: istanbul.

[gaguirre]

Totally agree. To be honest, I'm not actively maintaining this package (I mean, keeping it updated with latests tools, etc) so any PR is welcome.

[YasharF]

Removal of gulp-coveralls and (no longer needed) babel: #49

[YasharF]

Looking at dealing with gulp-istanbul which causes the istanbul deprecation warning, and taking a step back, after #49 what gulp is still doing is:

• eslint check
• code coverage report
• execute tests using gulp-mocha

With the latest/current npm, mocha, and nyc (istanbul cli replacement) these could be achieved without gulp, enabling removal of the dependencies on all of the gulp plugins such as gulp-istanbul which causes deprecation warnings. This can also eliminate the issue with isparta.
More specifically, eslint can run as a mocha task, and:

  "scripts": {
    "test": "gulp"
  },

needs to get replaced with

  "scripts": {
    "test": "nyc mocha --timeout=10000 --exit"
  },

I can submit a separate PR after #49 or combine it in the same PR. Let me know.