Selenium webclient create pd 11323

A couple of selenium tests for creating Projects and Datasets in webclient.

Tests the enabled state of createP/D/S buttons and right-click menu, as documented in Gus' word doc:
https://drive.google.com/?authuser=0&pli=1#folders/0B0o63qHVjgTQZHYwSGNMSTJRVDg

To test:
```
$ bin/omero web seleniumtest webclient localhost http://localhost:4080 chrome
```