Fix issue #40 and #41

Fix https://github.com/cescoffier/maven-play2-plugin/pull/40
Select the right artifact among proposals

Fix https://github.com/cescoffier/maven-play2-plugin/issues/41
Add parameters to enable / disable javadoc and sources attachment (disabled by default)

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>