In AngularJS how do I substitute minified javascript files with non-minified files in my development environment?

What is the best way to handle this in AngularJS?

I have an AngularJS app that includes concatenated/minified javascript files, however in my development environment I want to load the non-concatented/non-minified versions of the file. I want this because it is easier to debug the code with non-minified files.

<!-- production -->
<script src="js/all.min.js"></script> <!-- contains all concatenated/minified code -->

<!-- dev -->
<script src="js/services.js"></script>
<script src="js/controllers.js"></script>
<script src="js/directives.js"></script>

I am not sure how to do this since in AngularJS I couldn't find a conditional mechanism that is suitable. I had thought about using a directive on the each script tag?

I am using Gulp to concat and uglify the files, but I couldn't find a method to accomplish this with Gulp.

PHP is the server-side language.

Any help will be greatly appreciated.