Added plugins to wrappers

• Cookies are now unique across brokers on different ports.
• The experiment id is now incremented when experiments are submitted
• Updated broker for easier setup (broker port is no longer buried in
the server.js code)
• Updated agent for easier setup (agent port is no longer buried in the
javascript and html code)
• Moved agent ‘critical code’ into core.js. This will be useful for
updating the script file in future.
• Moved javascript from html into agent.js and reduced repeated code.
• Cookies are now unique across agents on different ports.
• Added plugins to agents
• Created lti (blackboard) agent plugin
• Created noauth agent plugin
• Added agent setup instructions