Support engine.worker.capacity.unbounded configuration

[jfallows]

-w 1

root@zilla:/# ls -l /var/run/zilla/
total 1050284
-rw-r--r-- 1 root root        80 Jun 15 01:12 bindings
-rw-r--r-- 1 root root   1048576 Jun 15 01:12 budgets0
-rw-r--r-- 1 root root 537001988 Jun 15 01:12 buffers0
-rw-r--r-- 1 root root 536871680 Jun 15 01:12 data0
-rw-r--r-- 1 root root    262912 Jun 15 01:12 events
-rw-r--r-- 1 root root    262912 Jun 15 01:12 events0
-rw-r--r-- 1 root root        12 Jun 15 01:12 info
-rw-r--r-- 1 root root       749 Jun 15 01:12 labels
drwxr-xr-x 2 root root      4096 Jun 15 01:12 metrics
-rw-r--r-- 1 root root        32 Jun 15 01:12 tuning

root@zilla:/opt/zilla# ./zilla metrics
namespace    binding    metric                        value
                        engine.workers.utilization        0
                        engine.workers.count              1
                        engine.workers.capacity       16384

-w 1 -Pzilla.engine.worker.capacity.limit=8192

root@zilla:/# ls -l /var/run/zilla/
total 1050284
-rw-r--r-- 1 root root        80 Jun 15 01:14 bindings
-rw-r--r-- 1 root root   1048576 Jun 15 01:14 budgets0
-rw-r--r-- 1 root root 537001988 Jun 15 01:14 buffers0
-rw-r--r-- 1 root root 536871680 Jun 15 01:14 data0
-rw-r--r-- 1 root root    262912 Jun 15 01:14 events
-rw-r--r-- 1 root root    262912 Jun 15 01:14 events0
-rw-r--r-- 1 root root        12 Jun 15 01:14 info
-rw-r--r-- 1 root root       749 Jun 15 01:14 labels
drwxr-xr-x 2 root root      4096 Jun 15 01:14 metrics
-rw-r--r-- 1 root root        32 Jun 15 01:14 tuning

root@zilla:/opt/zilla# ./zilla metrics
namespace    binding    metric                        value
                        engine.workers.utilization        0
                        engine.workers.count              1
                        engine.workers.capacity        8192

-w 1 -Pzilla.engine.worker.capacity.unbounded=true

root@zilla:/# ls -l /var/run/zilla/
total 1050284
-rw-r--r-- 1 root root        80 Jun 15 01:15 bindings
-rw-r--r-- 1 root root   1048576 Jun 15 01:15 budgets0
-rw-r--r-- 1 root root 537001988 Jun 15 01:15 buffers0
-rw-r--r-- 1 root root 536871680 Jun 15 01:16 data0
-rw-r--r-- 1 root root    262912 Jun 15 01:15 events
-rw-r--r-- 1 root root    262912 Jun 15 01:15 events0
-rw-r--r-- 1 root root        12 Jun 15 01:15 info
-rw-r--r-- 1 root root       749 Jun 15 01:15 labels
drwxr-xr-x 2 root root      4096 Jun 15 01:15 metrics
-rw-r--r-- 1 root root        32 Jun 15 01:15 tuning

root@zilla:/opt/zilla# ./zilla metrics
namespace    binding    metric                             value
                        engine.workers.utilization             0
                        engine.workers.count                   1
                        engine.workers.capacity       2147483647