Fix incorrect thread name

[bongole]

Fix incorrect thread name.

Before:

$ puma -t 5:5
$ ps -eT | grep puma
148652 148652 pts/0    00:00:00 puma
148652 148681 pts/0    00:00:00 puma 004
148652 148682 pts/0    00:00:00 puma 004
148652 148683 pts/0    00:00:00 puma 004
148652 148684 pts/0    00:00:00 puma 004
148652 148685 pts/0    00:00:00 puma 005

After:

$ puma -t 5:5
$ ps -eT | grep puma
148951 148951 pts/0    00:00:00 puma
148951 148980 pts/0    00:00:00 puma 001
148951 148981 pts/0    00:00:00 puma 002
148951 148982 pts/0    00:00:00 puma 003
148951 148983 pts/0    00:00:00 puma 004
148951 148984 pts/0    00:00:00 puma 005

[stereobooster]

Nice. Can you please rebase? Tests (at least Travis) were fixed in the master

[bongole]

@stereobooster Thank you for your review. I rebased to the latest master.