Rename QAbstractSocket::PauseOnNotify -> PauseOnSslErrors

Rename QAbstractSocket::PauseOnNotify -> PauseOnSslErrors

Although we created an enum for pause modes to make 5.x binary
compatible with 5.0, the enum value is not well named.
In 5.1, we propose to add PauseOnProxyAuthentication to the enum.
PauseOnNotify is not clear what it means, while PauseOnSslErrors is.

Any new notification in a minor release would need a new enum value
otherwise applications would get pauses they did not expect.

Task-number: QTBUG-19032
Change-Id: I4dbb7467663b37ca7f0551d24a31bc013968bedc
Reviewed-by: Richard J. Moore <rich@kde.org>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>