Update Gruntfile.js removing pointless reading of customize.html.

I couldn't see a reason to read "customize.html", removed line.
Merge pull request #10841 from DeanMarkTaylor/patch-1

Update Gruntfile.js removing pointless reading of customize.html.
Spelling mistakes in documentation.
Merge pull request #10855 from dan-silver/master

Spelling mistakes in documentation.
Update Gruntfile.js fixing undefined jQuery check

The check to see if jQuery was defined as incorrect causing the "Bootstrap requires jQuery" message to only be displayed if jQuery is defined and has a value which equates to `false`.
Merge pull request #10863 from DeanMarkTaylor/patch-2

Update Gruntfile.js fixing undefined jQuery check
rm unnecessary backslashes from jqueryCheck
Update qunit dependency
Merge pull request #10869 from ZDroid/patch-2

Update qunit dependency