Create symlinks with force flag

[Derrick Lin]

I think it should use ln -sf instead of ln -s when creating symlinks, or at least has an option to do that, otherwise it will fail when some of my config files are already symlinks pointing other files.

Relevant issue: #1797

[jamesrtnz]

PR #1929 enables an option which should make this work for you, btw; hopefully this will get merged at some point.