Added maintenance tab

• Updated the following functions to support access to multiple lab
servers and clients at the same time. Fixed the existing bug related to
javascript variable scoping.

> getLabConfiguration
> getLabStatus
> getEffectiveQueueLength
> cancel
> getExperimentStatus
> retrieveResult
> submit
> validate

• Added logging support
• Added switch statements

• Added new admin commands
> getBrokerLog - Returns the log string for the latest run of the broker
> getBrokerInfo - Returns an extended version of the broker info
(containing GUID)
> getLabInfo - Returns all the details about a lab server
> deleteLab - Deletes a lab server

• Added GUID to About tab in Admin panel
• Added Maintenance tab in Admin panel
• Added log file to maintenance tab
• Added logout menu option
• Added asynchronous wrapping to server loading
• Modified server loading (can load all servers at once)
• Updated logging to ignore GET/POST requests
• Added list of servers to maintenance page