Fix for binary file writing in __capture_screenshot

Hi,
I just started using wtframework.
So far I really like the structure of the framework, however I had a small issue.
The framework was taking screenshots, but I couldn't open them.
After a bit of research, I seemed to have found a fix -
In [capture.py](https://github.com/wiredrive/wtframework/blob/67ec0873522cf9ae46cc71fa7d18752c9c790d67/wtframework/wtf/web/capture.py) __capture_screenshot method, it seems the driver is always recognized as a remote driver, but that itself isn't the issue.
The issue is that you open the file in "w" mode. The fix was simple - open the file in "wb" mode, and the screenshots work.