Request for additional waits: checked(), selected(), disabled() ...etc.

While automating an internal application, I found myself having to write workarounds for some basic use cases. It's common that the user would want to check the state of form elements when automating UI or wait for the desired state condition to take place. One such case is the state of checkboxes.

I suggest adding the following waits to avoid the need for workarounds:
- checked()
- selected()
- disabled()
- containsHtml() (in contrast to .html() this is for partial matching)
- containsText() (in contrast to .text() this is for partial matching)

Let me know what you think!