make planet replication url configurable

make planet replication url configurable so we can use geofabrik's awesome daily country diffs

Changes include
1) Use settings for replication url and maxinterval
2) Update configuration.txt with these settings
3) Change regexs to support file listings from planet.openstreetmap.org and download.geofabrik.de
4) Explicitly sort directory listing by date descending as planet.openstreetmap.org and download.geofabrik.de default behavior's differ