Add a way to link to the latest version directly about distributions

[Kubuxu]

Maybe use js trickery to update visible, clickable links on the website.

So there would be file current which will contain version number of the most recently released full version. Then on website link: go-ipfs_current_linux-386.tar.gz which will work but when someone has js enabled (90% of cases) it will be rewritten to go-ipfs_$(cat current)_linux-386.tar.gz (I am using shell syntax but it would be done in js).

If someone has no js enabled he will be left with go-ipfs_current_linux-386.tar.gz which should also work.

Other solutions would require changes to the protocol and it might be quite useful feature, to be able create redirect links, but I don't think it should be focus now.