improved readme
improved vagrant configuration

* I stumbled upon problems with the cookbooks path variable and had to set it
  explicitly.
* Added support for samba to export the new user's home directory.
improved my personal stuff

- use username provided by vagrant to be more flexible with different username
  schemes (gfrey vs. gerfre).
- fixed bug with git (make root directory world accessible) that should be gone
  with git 1.8.3 version.
added support for branches to mdenvy's LWP git resource