Allow to override useNativeGit property of the gitcommitid plugin

the git commit id plugin exposes the useNativeGit property to control, if it should use JGit (false), or native Git executable. Right now, Zeppelin project doesn't override it, so by default it uses false, enforcing the JGit implementation.

The problem is that JGit doesn't work with git worktree checkouts that are very handy to work with the several trees in parallel.

It would be nice to expose property that could be overridden from the command-line, without modification of the pom.xml.