Silvertip 0.4.0

Signed-off-by: Bob the Builder <releng@valotrading.com>
Silvertip 0.4.1-SNAPSHOT

Signed-off-by: Bob the Builder <releng@valotrading.com>
Merge pull request #47 from valotrading/releases/0.4.0

Release 0.4.0
Add 'EventSource#isClosed' back

Reviewed-by: Pekka Enberg <penberg@valotrading.com>
Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>
Add 'Events#close'

Reviewed-by: Pekka Enberg <penberg@valotrading.com>
Signed-off-by: Jussi Virtanen <jussi.virtanen@valotrading.com>