Insert a BOM check for import and file upload

* Similar to @janekptacijarabaci fix in greasemonkey/greasemonkey#1940
* Fix compliance with STYLEGUIDE.md and usage of pre-initialized identifiers
* Currently **do not** propagate BOM *(Byte Order Mark)* with meta routine ~~or user.js source with and without installation count increment~~ *(whoops it does the part striked out of this by default but everyone should get my point with the meta routine... e.g. doesn't appear to be needed in there)*
* BOM currently shows up in Ace as a exclamation triangle with "This character may get silently deleted by one or more browsers" on dev.

**NOTE**: Many thanks to the report by @cvzi and applies to #200 and partially outlined in #198.

---
Tested on dev with [this script](http://localhost:8080/scripts/Marti/UTF8_BOM_test_%C3%B6_%E8%B4%B4%E5%90%A7%E6%A8%A1%E7%BB%84%E5%B1%8F%E8%94%BD) in `Mozilla/5.0 (X11; Linux x86_64; rv:32.0) Gecko/20100101 Firefox/32.0`