Solution was running uglify task with mangle option set to false.
ie: .uglify({mangle: false})
whole code:
gulp.task('scripts', function() {
return gulp.src('app/js/**/*.js')
.pipe(jshint('.jshintrc'))
.pipe(jshint.reporter('default'))
.pipe(concat('main.js'))
.pipe(ngmin())
.pipe(gulp.dest('app/dist/js'))
.pipe(rename({suffix: '.min'}))
.pipe(uglify({mangle: false}))
.pipe(gulp.dest('app/dist/js'))
.pipe(livereload(server))
.pipe(notify({ message: 'Scripts task complete' }));
});