Added work around for RODBC 1.3-10 returning factors for (PostgreSQL)
   double precision in R-3.1.0 but not in older R versions. This is 
caused by an intended change to type.convert() in R.

git-svn-id: svn://svn.r-forge.r-project.org/svnroot/tsdbi@507 edb9625f-4e0d-4859-8d74-9fd3b1da38cb