Going from text to clob is not something we do.

Also Oracle DB has problems with this, see
http://abhijitbashetti.blogspot.de/2011/10/converting-varchar2-to-clob-and-clob-to.html

Conflicts:
	tests/lib/dbschema.php
enable oci in autotest.sh
Merge pull request #3984 from owncloud/enable_oci_testing_stable5

Enable oci testing stable5