Unfortunately as of June 8th, Google CL is broken, so the upload to google photos no longer works.  According to the developer's website this is likely not something that will be fixed. (Source: https://code.google.com/p/googlecl/)

Because of this and the feedback Dave provided, I am reworking parts of this script.  If you are interested in following the changes, please keep an eye on the github gist where the changes will be posted.