Replace "project" with "project_id" in clients lib

Fixes #24
Fix typo in "load_image_meta" (cmds.image)

Closes #27
Manage logs when log file is not accessible

Fixes #25

If the default log file location is not accessile, inform user
about the error (e.g., no write permission, location does not
exist). Also, make non-debug log messages shorter and make sure
all instructions and warnings are printed to standard error.