include configuration settings when generating file cache hash

We had an issue where we had some non-minimizable angular code, and had already compiled/deployed it.      We adjusted the minify settings to not mangle method parameter names.  The compiled assets were fixed, but they had the same hash as the old compiled files, so browsers didn't load up the corrected files.

This change factors in the assets configuration into the file hash generation so that if the config changes, it will generate a different hash even if the source file hasn't changed.

The ```byte[] concat``` method is generic, so it could go into some other utility method (or is there a library for this already available?).

I considered caching the ```configBytes```, but the current implementation didn't add any time in our project (it was 19 seconds to compile all our project's assets before and after this change).