Default use_altitude_tag to True
Default use_altitude_tag to True

Summary: Set `use_altitude_tag = True` by default in the `config.py`. This should also solve problems like this [github issue](https://github.com/mapillary/OpenSfM/issues/918), where images are taken several meters above ground, e.g. by a drone, and points actually on the floor are then at a negative distance.

Reviewed By: YanNoun

Differential Revision: D37481946

fbshipit-source-id: 10247e1afca8c8f0aa31d693f2e14115cf238f89

mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM,mapillary/OpenSfM