Rename Google Analytics variables

`i` `s` `o` `g` `r` `a` `m` -> `s` `y` `n` `c` `I` `t`

It is generated by [isogram](https://github.com/shinnn/isogram), a google analytics code generator used by [gulp website](https://github.com/gulpjs/gulpjs.github.io/blob/fc2a237ef4b476dd9428fce0da77c6bd3f8b925d/index.html#L134).

If you prefer other word, I'll fix this PR.

* `s` `y` `n` `c` `Y` `o` `u`
* `b` `r` `o` `w` `s` `e`

etc.