Add support for encrypted maven credentials

[Smasherr]

In many situations, when working with private repositories, there is a need to use encrypted maven credentials. Such setup requires having the file settings-security.xml additional to settings.xml in ~/.m2. Hence, I propose to modify the maven binding to include both files.

The implementation would be quite simple since the security settings can be passed to Maven with the system property settings.security. For instance:

mvn -s ~/.credentials/settings.xml -Dsettings.security=~/.credentials/settings-security.xml package