If you want to use ft_extract
function, it currently has
two options for how to extract text from PDFs: xpdf and ghostscript.
See http://www.foolabs.com/xpdf/download.html for instructions on how to download
and install `xpdf`. For OSX, you an also get `xpdf` via
Homebrew (https://github.com/homebrew/homebrew-x11/blob/master/xpdf.rb) with
brew install xpdf
. Apparently, you can optionally install Poppler, which is
built on xpdf. Get it at http://poppler.freedesktop.org/
See http://www.ghostscript.com/doc/9.16/Install.htm for instructions on how to
download and install `ghostscript`. For OSX, you an also get `ghostscript` via
Homebrew (https://github.com/Homebrew/homebrew/blob/master/Library/Formula/ghostscript.rb)
with brew install gs