Add option to merge .osm files

[planemad]

Allow single file .osm output by merging different files with osmosis

[baditaflorin]

@planemad i have made a fork that will merge the files and output just one file per user, using a different approach. First i download all then i filter, because i see that the filtering process taks more time then the merging of the osc files

You can try it here and give feedback https://github.com/baditaflorin/osm-history-processor/blob/master/peer_review.py

It`s hardcoded for a period of time of 5 days.