Changes to upgrading and getting lein-deb to work with clojure 1.5.1

1) Upgraded to using clojure/1.5.1, involed removing clojure.contrib deps
2) Added a sample.project.clj to illustrate a working example of lein-deb
3) Document
since you're in here - please update these to use `require :all` - should be easy to change. I'd also prefer indentation that matches https://github.com/bbatsov/clojure-style-guide, eg:
```clj
  (:require [clojure.string :as s :refer [blank?]]
            [clojure.set :as set]
            [clojure.java.shell :as sh])
```