Added asset entry when installing component from discovery

When installing a component via discover_install the correspondent entry in table #__assets is not created.

How to reproduce the problem and/or test the patch::
Install any component that creates an asset entry on normal install via discover install and check whether there is an entry for that component in #__assets.

This is the Joomla 3 fix.  The Joomla 2.5 fix is in http://issues.joomla.org/tracker/joomla-cms/2585.

There are additional test instructions in the old PR: http://issues.joomla.org/tracker/joomla-cms/2586