Figure an efficient way to test is external drive is full

[aurelient]

No description provided.

[aurelient]

TODO: use the errno module.
Wrap the screenshot writing code between try catch and check if the error is:
errno.ENOSPC = No space left on device

If this case logging should be disabled and an alert displayed.

https://docs.python.org/2/library/errno.html

[acrule]

Still have three bugs

1. Some sqlalchemy Operational Errors are still not caught
2. Image IO Error: PNG write error (when taking ESM screenshot)
3. When the drive is full Selfspy continues to take screenshots but does not save them to the drive