Updated the WebDriverWaits to use self.timeout

After unwinding an intermittent failure that was occurring when <code>test_that_selecting_exact_version_doesnt_show_other_versions()</code> was run against stage; I noticed that we had hard coded two <code>WebDriverWaits</code> to <code>10</code>. Not sure if this completely remedies the intermittent failures due to the test timing out but it appears to be a start.

@AlinT, you're closest to Socorro automation. Does this look correct?