Release v0.6.0

[sotetsuk]

• Add test
• Enable to choose "waiting" jobs in the options for stopping a job #70 Enable to choose "waiting" jobs in the options for stopping a job
• Stop using print #40 Stop using print
• Add no column title option to jobs subcommand #73 Add no column title option to jobs subcommand
• Automatic token update fails #43 Automatic token update fails
• Show (error) message for the failed job submission #72 Show error message for (failed) job submission
• Fix time expression in job list #68 Fix time expression in job list
• Check return code of sub commands #64 Check return code of sub commands
• Add --vc=XXX option to jobs subcommand #71 Add --vc=XXX option to jobs subcommand
• To specify item, use (username, jobname) instead of jobname  #59 To specify item, use (username, jobname) instead of jobname
• delete username option in SSH #54 Delete username option in ssh (or make sure it works)
• Fix save path of ssh key #37 Fix save path of ssh key
• Enable lowercase for state specification of jobs subcommand #41 Enable lower case for state specification of jobs subcommand
• SSH fails when there are two same name jobs #48 SSH fails when there are two same name jobs