Fix problem with pip install git requirement

Your module is really great, but when I have run it in my environment (Ubuntu 12.04.3, Python  2.7.3, Pip 1.4.1, Git 1.7.9.5) it failed to install requirements. Puppetboard has one git requirement and it fail with following message:
```
Command /usr/bin/git clone -q git://github.com/nedap/pypuppetdb.git /var/www/puppetboard/virtenv-puppetboard/build/pypuppetdb failed with error code 128 in None
```
I have default config for class
```
    class { 'puppetboard': 
        basedir => '/var/www/puppetboard',
        require => [Package['git'], Class['python']]
    }
```
So I have found that add correct 'cwd' to puppetboard repository fix my problem, but I'm not python dev so I'm not sure in this fix.