Put multiple devids in create_close

Still experimental, but it seems like it works.

In `create_close`, instead of `devid=9&path=http://someserver/dev9/1/2/3/123.fid`, you can now specify multiple devs/paths like `devid_1=9&path_1=http://someserver/dev9/1/2/3/123.fid&devid_2=42&path_2=http://someotherserver/dev42/1/2/3/123.fid`, and mogilefsd will write all of those devs to the DB.