deps: fix git case sensitivity issue in npm

Remove Readme.md, as the subsequent npm update commit creates a
README.md. Combining the create and delete operations into the
same commit leads to OSX machines running into issues – they
don't detect it as a rename, instead trying to create a new
README.md, which fails because Readme.md hasn't been deleted yet.
This causes the entire operation to fail spectacularly. Thus,
the delete operation is performed first, in this commit, then
the create operation follows in the npm update commit.

PR-URL: https://github.com/iojs/io.js/pull/1456


Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>