Some improvements to geo api

This pull request has the following geo-api related updates:
1. Give useful debug log messages in cvmfs download client if Content-Length is less than data received.
2. Always add Content-Length header in geo api response.  I thought it was automatic, but now I think it must be only under some circumstances.
3. Add a small development testing python program for the webapi
4. Reduce cache expiration from 3 days to 1 hour