Move features directory to trash on clean
Move features directory to trash on clean

Clean should return the data directory to the initial state.
Currently the features directory is is not cleaned. This patch
fixes that behaviour.

oscarlorentzon/OpenSfM,sunbingfengPI/OpenSFM_Test,BrookRoberts/OpenSfM,BrookRoberts/OpenSfM,mapillary/OpenSfM,oscarlorentzon/OpenSfM,BrookRoberts/OpenSfM,mapillary/OpenSfM,BrookRoberts/OpenSfM,oscarlorentzon/OpenSfM,oscarlorentzon/OpenSfM,sunbingfengPI/OpenSFM_Test,mapillary/OpenSfM,sunbingfengPI/OpenSFM_Test,BrookRoberts/OpenSfM,oscarlorentzon/OpenSfM,sunbingfengPI/OpenSFM_Test,mapillary/OpenSfM,mapillary/OpenSfM,sunbingfengPI/OpenSFM_Test