For the purpose of this exercise, we'll install Jenkins CI server on the development machine to preserve resources. Normally this service would reside on its own server where all developers in the team could access it.
I recommend increasing the memory allocation of the CentOs dev/build machine to at least 1536mb if you can, this will speed up all operations once Jenkins is installed.
Follow instructions here:
Follow these instructions to change jenkins user to vagrant.
Restart the jenkins service to ensure changes take,
Note that you need "Show" the desktop from Virtual box GUI before firefox can run.
Make sure you can open firefox with a Jenkins script.
Create a freestyle project and add a build step with the following shell script:
export DISPLAY=:0
firefox
Running this project should open a new firefox window on your CentOs desktop.
Grunt build and your ssh deployment script should now run without problems.