Dataset changes and data upload validation

Covers issues:
* https://github.com/KSHSK/WAVED/issues/115 - Validation and error displaying for data upload popup
* https://github.com/KSHSK/WAVED/issues/116 - Use knockout for data upload popup

Work done:
* The Data Upload dialog now has validation and error displaying, taking care of the above issues.
* Now DataSet uses just the filename and {create/load}Project.php returns the data folder path which the filename is appended to when data is read. This will make Save As easier because the data folder path (which has the project name) will never be saved, so there is less state to change when doing Save As.