Automatic assignment of dsids

• implement logic to only assign blocks of DSIDs
• test 1: 10 DSIDs that don't fill in a gap
• test 2: continuous set of DSIDs that fills in a gap
• test 3: 1 DSID should be assigned to the lowest possible DSID

Once the above works

• test git fetch origin master && git checkout -b new origin/master - if it works replace in master

• implement flag for specifying branch name (--branch)

• replace -n with --dry

• implement flag for moving DSIDs but not pushing to git (--nogit)

• keep track of the DSIDs that have changed and suggest the command to run after dry run

• update list of DSIDs in commit script (provided with -d argument)

• Update README