Non-deterministic order of gulp streams causes potential build hash change

[scottohara]

The order of gulp streams is not guaranteed (see gulpjs/gulp#687, and here).

This can sometimes cause gulp-concat to produce a different file (which in turn causes gulp-rev to produce a different hash), even when the source files are unchanged.

The long term solution for this is obviously to move away from concatenating scripts, and to start using modules and bundler such as webpack.

As a short term fix, an attempt was made to use gulp-sort to reorder the streams, however this was rolled back because it broke the build.

[scottohara]

This becomes redundant with the move to webpack