Remove 'update_project_metadata.py' utility and put useful functionality into 'update' command

[pjbriggs]

The update_project_metadata.py utility should be removed as it is rarely used and could now be considered unsafe with the implementation of the new auto_process.py update command (as metadata changes by the former would most likely be overwritten by the latter).

Potentially useful functionality could be incorporated into the update command, for example allowing programmatic updates to the project metadata which would ensure that changes are correctly synchronised. It might also be useful to be able to set data items such as biological samples from the command line.