The remotely run script is moved into a new subdir called "external",
where external utils to be used by osmo-gsm-tester (exernal to its own
process) are placed.
It needs to be in another directory because python files in obj/ are
loaded at startup of osmo-gsm-tester to dynamically load schemas.
Change-Id: I633a85294694f2c6efd58535729e9b8af166b3ff