This plugin will allow you to transfer crew members between modules on the same vessel using the same method as transferring fuel. Just select the parts you want to transfer crew between, and click "Transfer 'Kerbal Name'".
Forum Thread: http://forum.kerbalspaceprogram.com/threads/82101-0-23-5-Kerbal-Crew-Transfer
Github Repo (Report Bugs Here): https://github.com/joedavis/CrewXfer