Only make the control connection in worker #0

(if this worker ever dies, a new one will be spawned as #0)
not-quite-working code to put the hash in shm
Safety around storing a delay failing due to out-of-memory
Alloc the hash pointer from shm so that it's shared properly

without this, when one process does HASH_ADD_STR and modifies the
pointer, other processes don't see it.

ngx_http_smockron_delay_hash is now a handle (delay**) instead of a
pointer.
Merge branch 'single-control-sock'

Fixes #8