Npm: Fixed mocha and gulp-uglify vulnerabilities

[RunDevelopment]

This brings mocha (2.2.5 -> 5.2.0) and gulp-uglify (0.3.1 -> 3.0.1) to the latest versions and fixes 5/11 vulnerabilities.
(I only changed package.json)

Almost all minified are different because of the uglify update.
Keep in mind merging this will create conflicts for almost every other PR because of the minified files.

I will upgrade gulp (3.8.6 -> 4.0.0) once this and #1741 are through because gulpfile.js has to be changed.

[mAAdhaTTah]

Didn't we upgrade to gulp 4 already?

[RunDevelopment]

Yes, but only gulp. This updates mocha and gulp-uglify.

[mAAdhaTTah]

Can we go straight to mocha@6?

[RunDevelopment]

I updated all dependencies now and everything works just fine.

I just wonder why the minified files changed again...