Add a way to configure permissions on deployed files

[actually maven-artifact-manager..?]

Since my umask = 077, m2 deploy stores files in the remote repository that aren't accessible
by httpd.

I need to provide file permissions in the repository configuration in the pom or in the settings.xml
server definitions (perhaps the repo's, but permissions should go with authentication information I think).

Wagon already supports filemode and group settings on it's Repositories. DefaultWagonManager doesn't provide a way
to fill those settings.