OMERO.matlab improvements (rebased onto develop)



This is the same as gh-742 but rebased onto develop.

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This PR addresses issues raised by @bramalingam and adds documentation for some recent changes added to the toolbox:
- adds a top-level link to the Training examples directory
- states a session needs to be created to create an unsecure client
- exposes some of the parameter/value options in the `get<object><type>Annotations` functions in the documentation
- fixes whitespaces and capitalize MATLAB