Add the command "git pt ID" to name branches from Pivotal Tracker tasks

This is the expected output:

$ ./bin/git-pt 49924493
Finding your project and story....
Found story 49924493 in 'Host SQS - Mobile'
This is the suggested branch name. Press enter if you agree, rewrite again if you want another one:
host-sqs-mobile/checkin/out-times-per-booking-49924493

git co -b host-sqs-mobile/checkin/out-times-per-booking-49924493
Switched to a new branch 'host-sqs-mobile/checkin/out-times-per-booking-49924493'