Added printpostget proxy

Salut Andreas

Even though the use-case is quite rare, a postget-proxy has been added.

Kind regards,
Tobias



 WTH - why use a postget-proxy for printing? 
1. the maximal URL-length of IE is 2083 signs (http://support.microsoft.com/kb/208427/en)
 2. sometimes giant QGIS-project with a lot of layers are realised (print-URL-length > 2083 signs)
 3. apache dicards POST data on redirect

if once in a blue moon it comes to this rare case, there is a solution: 
 a. configure printpost.wsgi 
 b. set "method":"POST"
c. fill in the URL to the proxy "url_proxy":"http://www.urltoproxy/printpostget.wsgi?