Use UTC instead of GMT.

GMT shouldn't be used anymore and for non-scientifical purposes it is allowed to simply replace GMT with UTC.

There was one string that looked too scary for me to start modifying in `lib/xdate.dev.js`:

```
proto.toUTCString = proto.toGMTString = function(formatString, settings, uniqueness) {
```

* https://en.wikipedia.org/wiki/UTC
* http://geography.about.com/od/timeandtimezones/a/gmtutc.htm


--

Squashed commit of the following:

commit 8f4b3410e1a6c3169fbe42b58c1cb419b665756f
Author: Mikaela Suomalainen <mikaela.suomalainen@outlook.com>
Date:   Sun Jun 1 13:46:24 2014 +0300

    classes/LogReaders/*: s/GMT/UTC/

commit b1bb8f4f4befa89e0b86c7361ac9df8b70d1af88
Author: Mikaela Suomalainen <mikaela.suomalainen@outlook.com>
Date:   Sun Jun 1 13:45:40 2014 +0300

    classes/JSIS.js: s/GMT/UTC/

commit 8ed1cf7b960b88b73dd275a2d6f52bf28b566da2
Author: Mikaela Suomalainen <mikaela.suomalainen@outlook.com>
Date:   Sun Jun 1 13:44:57 2014 +0300

    config.example.js: s/GMT/UTC/