Example "model_browser" fails.

[jjmontesl]

The example model_browser fails with:

  File "/home/jjmontes/git/cubes-master/examples/model_browser/application.py", line 32, in report
    mapper = browser.mapper
AttributeError: 'SQLBrowser' object has no attribute 'mapper'

An attempt to fix this was #305. But while that fixes the first screen, model_browser failed at the next step when showing dimensions:

  File "/home/jjmontes/git/cubes-master/examples/model_browser/application.py", line 37, in report
    logical = attribute.ref()
TypeError: 'unicode' object is not callable

So the example needs to be updated for Cubes 1.1 or removed.