create metadata table in MBTiles caches
add update_metadata method to MBTilesCache
remove import error warning for shapely
added documentation for new option in 'refresh/remove_before'. get modification time from file
fixed bug, second parameter wasn't passed over to load_ogr_datasource
added from_file option to seed-config spec
read the modification time of a given file and use this for refresh/remove_before while seeding/cleaning up
read the modification time of path
added test for refresh/remove_before with file, fixed paths in corresponding seed.yaml.
load the seed file with local_base_config
document directory option of file cache
add EPSG:3857 to WMS default SRSs
remove UTM and GK from default WMS SRS
remove 'mixed' from wms image_formats list
Update doc/tutorial.rst
Merge pull request #45 from drnextgis/master

Fix services section name in tutorial
Update doc/tutorial.rst
Merge pull request #46 from drnextgis/master

Fix docs typo
fixed service:/services: typo
renamed .from_file to .mtime
fixed loading of timestamp from missing file