Restore the oml.platform.updatesite

[NicolasRouquette]

Publishing the oml.platform.feature as an Eclipse update site provides a useful aggregate of all the necessary jars for running OML-based applications outside of Eclipse.

Note that this is not the optimal solution because there can be subtle jar conflicts for a java classloader if a given class name could be loaded from multiple plugin jar files (see #15).

The proper way to do this would be to convert Eclipse plugins into corresponding Maven artifacts such that plugin dependencies are translated into dependencies on the corresponding artifacts' poms.