git clone should use https URL in devenvironment.md

`git clone` should use `https` URL.

Before:
```
hybrid@node002:~$ git clone http://git@github.com/dotcloud/docker
Cloning into 'docker'...
error: The requested URL returned error: 403 while accessing http://git@github.com/dotcloud/docker/info/refs
fatal: HTTP request failed
```

After:
```
hybrid@node002:~$ git clone https://git@github.com/dotcloud/docker
Cloning into 'docker'...
remote: Reusing existing pack: 40213, done.
remote: Counting objects: 120, done.
remote: Compressing objects: 100% (109/109), done.
Receiving objects: 100% (40333/40333), 21.81 MiB | 978 KiB/s, done.
remote: Total 40333 (delta 61), reused 37 (delta 11)
Resolving deltas: 100% (25061/25061), done.
hybrid@node002:~$ 
```