Support for Eliptic curves cryptography

[morzan1001]

I know this project hasn't been updated in a while, but I'm posting this issue in case other people are having problems sending messages. It took me some time to figure out why I couldn't send messages to my Mattermost but I saw in the logs of the Sonarqube that the error javax.net.ssl.SSLHandshakeException: Received fatal alert: handshake_failure is thrown. After some research and trial and error I found out that TLS1.2 is supported but when the server requests ECDSA cryptography for encryption using TLS, the SSL handshake fails. So I have allowed other cryptography on the server and everything works fine.

I suppose the whole thing would be quite easy to fix by updating dependencies, but since I use the whole thing only in internal networks it is oke to allow other cryptographic methods for now. If the Mattermost or Slack server is on the Internet, I would reconsider.

Small disclaimer, I can not say whether the problem comes from Sonarqube itself or from this plugin, so exactly I have not read the plugin code ;)