Update default timeout to 30 seconds

Submitted for discussion.

We seem to have frequent intermittent failures due to slow connections and slow loading times of apps/pages. It seems to me like it would be a good idea to bump up the default timeouts from 10 to 30 to address this.

Because we have both positive and negative wait_for methods (e.g., wait_for_element_displayed and wait_for_element_not_displayed), we shouldn't have any situations in which a test has to wait the full timeout period unless an actual problem is present, so I don't see much harm in this.

What does everyone think about this?