Popen does not accept intervals arguments with spaces

Not sure when this broke, but the problem seems to be that we pass the interval as a single element in the argument list, when each word should be its own element.

For example, we give:

['timew', 'track', 'from 20190304T164355 - 20190304T170855', 'my tags']

when we should give:

['timew', 'track', 'from', '20190304T164355', '-', '20190304T170855', 'my tags']