A tweak to the previous Minify Notification Update #54

[amiga-500]

I had forgotten to increment the minify version when the minify cache was also cleared. I had only incremented it when the page cache was cleared. Although in most cases it is the page cache that when cleared (say, due to a plugin removal) it should be incremented, but for cases where the user adjusts their minify settings to say smaller file length sizes, it can potentially result in different minify file names and so its best to also increment the version variable for this case too -- i forgot about that.

I also moved the minify version update function into the define.php file so the function could be accessed from one central location instead of being duplicated twice (for pg cache class and minify class).