Rename samplesInPlate to sample
PlateService: Added getPlateList function for filtering lists
InvestigatorController: Clear flash.message
PlateController: Refacted list() to use PlateService getPlateList

Also store search variables into flash scope for Export function
PlateController: Refactored render_listPlate96() to use PlateService
PlateController: Refactored render_listPlate384 to use PlateService
PlateController: Added export plate list function (accessed from the list view)
PlateController: Moved logic for finding next highest plate Id into PlateService
PlateController: Added flash.message and fixed redirect but after creating plates
Controller: Clear flash.message
SampleService: New class. Added getsampleList()
PlateViewList: Updated variable names
PlateCreate384View: Added some client-side input validation
PlateService: Changed getHighestPlateNumber(..) into getNextHighestPlateId(..)
SampleListView: Moved sample list into a render template
Minor code clean-up