Suppress verbose messages from port allocation by default

This will suppress the 'ports' message during `gear list-units`:

```
[root@dev vagrant]# gear list-units
ports: searching block 41, 4000-4099
ID                   SERVER  ACTIVE  SUB     LOAD    TYPE

```

You can turn the messages on just by exporting the 'GEARD_VERBOSE' environment variable. @smarterclayton -> do you think we can use that ENV var on more places, to turn off the debug messages?