(QENG-1182) Add node to classifier prior to adding pe_repo class

Prior to this commit, beaker would make the assumption that a node had
already checked into the classifier. This commit changes that by
ensuring that the node is in the classifier before giving it the pe_repo
class.
Merge pull request #443 from briancain/maint/master/add-node-to-classifier

(QENG-1182) Add node to classifier prior to adding pe_repo class