Fix bfGetReader for MATLAB R2009a and earlier

Following the http://lists.openmicroscopy.org.uk/pipermail/ome-users/2013-September/003912.html and http://lists.openmicroscopy.org.uk/pipermail/ome-users/2013-September/003910.html threads, this pull request patches the `bfGetReader.m` function to allow it to be used with Matlab versions earlier than R2009b.

As a first implementation of this patch, the version check is performed using Matlab built-in `verLessThan` function available with MATLAB Version 7.4 and subsequent versions rather than using/maintaining the `versionCheck()` sub-function.

Such an implementation of the version check practically means we would drop support for versions of MATLAB earlier than 7.4 (R2007a). Consequently the typecasting workaround in `bfGetPlane` for earlier versions of Matlab than 7.1 is also dropped as part of this PR.

We may also want to expose a minimal version in the documentation page /cc @hflynn