Allow version builtin to run without git repository

The version builtin should be able to run without a git directory to call
it from wherever you want.

Change-Id: I1a3bce662e6788b860a275ee50315af8d5cc094a
Signed-off-by: Benjamin Muskalla <bmuskalla@eclipsesource.com>

org.eclipse.jgit.pgm/src/org/eclipse/jgit/pgm/Version.java

@@ -55,4 +55,9 @@ class Version extends TextBuiltin {
 
 		out.println(MessageFormat.format(CLIText.get().jgitVersion, pkg.getImplementationVersion()));
 	}
+
+	@Override
+	protected final boolean requiresRepository() {
+		return false;
+	}
 }