Unexpected behaivor on Russian keyboard layout

[In your code](https://github.com/developit/tags-input/blob/master/src/tags-input.js#L7) you use key codes to determine which key was pressed. But on Russian keyboard layout we have letter `б` on 188th key code. For example, if I type `яблоко` which means `apple` in english, I get this result:



首先阅读第 7 行的 src/tags-input.js，并使用俄语键盘布局输入 яблоко 来复现该问题。将报告的键码 188 的按键处理与正常文本输入进行比较；完成的标准是可以输入俄语字母而不会触发错误的标签行为。

由索引模型根据 Issue 内容生成。