gulp-useref for IONIC 1 project for Concatenation

[mayurm-virtueinfo]

Hi,
I am facing projblem for 2 days. I cannot impelement gulp-useref to concatenate js files in a IONIC Demo project. I am sending you ionic project in attachment please check following file that i have listed below.

index.html
gulpfile.js
ionic.project
Please help me to resolve this project. I have search around all about ionic but did not get rid of this.

Demo-Concatenate-JS-CSS.zip