BF: demos, ENH: datastore names

- updated .gitignore to not include files created for running iohub
demos

- changed iohub keyboard example so that CTRL + Q works on all platfoms
(none need SHIFT also pressed now)

- changed print in launch_iohubserver.py example

- Changed launchHubServer so that if DataStore is used, the file name is
either equal to the experiment_code or equal to value of datastore_name
kwarg if provided. This fixes issue when multiple demo scripts are in
same folder and also create DataStore hdf5 files (no name conflicts by
default.)