Changing the python module name

Changing from completion to ligo_channels.
Also changed the function names from complete to completion.
3 jobs for master in 11 minutes and 51 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build And Test
passed #247039
ligo-channel-completion:buster

00:02:07

passed #247041
ligo-channel-completion:jessie

00:11:50

passed #247040
ligo-channel-completion:stretch

00:02:01