Allow user to choose the lusitanian/oauth version

If you want to specify which lusitanian/oauth version to use, you will get the following error:

````
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - hannesvdvreken/oauth dev-master requires lusitanian/oauth dev-master -> satisfiable by lusitanian/oauth[dev-master].
    - hannesvdvreken/oauth dev-master requires lusitanian/oauth dev-master -> satisfiable by lusitanian/oauth[dev-master].
    - Can only install one of: lusitanian/oauth[v0.2.2, dev-master].
    - Can only install one of: lusitanian/oauth[v0.2.2, dev-master].
    - Installation request for lusitanian/oauth 0.2.2 -> satisfiable by lusitanian/oauth[v0.2.2].
    - Installation request for hannesvdvreken/oauth dev-master -> satisfiable by hannesvdvreken/oauth[dev-master].
```