It looks like the nuget is not restored during your build or probably the paths are not correct. I would suggest you go to your Workspace in Jenkins and check if the files are restored under this path:
C:\Program Files %28x86%29\Jenkins\jobs\Test\workspace\\packages\OpenAccess.CodeFirst.2013.3.1211.3\tools\enhancer\enhancer.exe
If they are not please check if you have enabled the nuget package restore during build for you solution, if it is not, enable it. Also I would suggest you to update the nugets to the current ones, you should uninstall the old version (OpenAccess.CodeFirst) of the nugets and install the Telerik.DataAccess.Fluent nuget instead. there are not braking changes between both of them.
I hope this helps.
OpenAccess ORM is now Telerik Data Access
. For more information on the new names, please, check out the Telerik Product Map