Downstream synchronization for rsync_project.

rsync_project signature includes new 'upload' parameter with default
value 'True' so to keeps backwards compatibility. When set to 'False',
local directory is synchronized with remote, instead of the other way
around.

Implements issue #845.

Here is a [script](https://gist.github.com/apbarrero/5071643#file-test_rsync-py) testing the feature and the [output](https://gist.github.com/apbarrero/5071656#file-gistfile1-txt) when run in my system.