Clean up js.js along suggestions from scrutinizer-ci, fixes #8204.

Also used JSHint.com to find a few other issues.

-Strict comparisons (===)
-Fixed regex escaping errors
-Refactored OC.buildQueryString to use jQuery.map
-Missing semicolons
-Braces around if block

Left some of the mixed spaces/tabs as they are for alignment in comments.
Merge pull request #8213 from cbojar/master

Clean up js.js along suggestions from scrutinizer-ci, fixes #8204.