Hardening/135

Implements the issue https://github.com/telefonicaid/fiware-connectors/issues/135

In addition to the `doc/operation/cygnus_01_to_0.*_migration.md` documents, the translation scripts have been modified in order a not sudoer user may run them.

Minor changes have been made in the translation scripts README and in the `doc/operation/ngsi2cosmos_migration.md` document, which references the translation docs.
It does not explicitely check if the paths are equal, but it checks if the destination already exists, and if it is epty or not. In this case, the script will exit with a "hdfs://locahost$dstHDFSFolder already exists and is not empty!"