Fix the installation instructions
Fix the installation instructions

As reported by mrjcleaver the installation did not work as described in
the README.md because the make-script cannot find the dependencies
if the project was not cloned into the GOPATH.

So the best solution is to install dee-cli using go get:

  go get -u github.com/andreaskoch/dee-cli

Resolves issue #1

andreaskoch/dee-cli