Improve boolean handling

In library there is this code:

   def set_ignore_implicit_angular_wait(self, ignore):
        if not is_boolean(ignore):
            raise TypeError("Ignore must be

But it might be better to use Robot Framework or SeleniumLibrary is_truthy method to improve boolean handling. SeleniumLibrary method is in here: https://github.com/robotframework/SeleniumLibrary/blob/master/src/SeleniumLibrary/utils/types.py
And it has been there since 3.0 release.

SeleniumLibrary boolean handling is explained in here: http://robotframework.org/SeleniumLibrary/SeleniumLibrary.html#Boolean%20arguments

I can provide you a pull request to fix the problem. Should I copy paste the implementation or can I use method from the SeleniumLibrary? If I can, it will raise minimum required SeleniumLibrary to 3.0.

从 issue 中所示的 set_ignore_implicit_angular_wait 方法开始，然后阅读 SeleniumLibrary 的 types.py 以及其布尔参数文档。确认支持的布尔值，以及项目是否可以使用 SeleniumLibrary 3.0；当此设置接受预期的布尔形式并一致地拒绝无效值时，即表示完成。