Bunyan

- Ensure that stderr from the dtrace child process (when using `bunyan -p PID`)
gets through. The `pipe` usage wasn't working on SmartOS. This is important
to show the user if they need to 'sudo'.

- Ensure that a possible dtrace child process (with using `bunyan -p PID`) is
terminated on signal termination of the bunyan CLI (at least for SIGINT,
SIGQUIT, SIGTERM, SIGHUP).

- Add `bunyan -p PID` support. This is a convenience wrapper that effectively
calls:

dtrace -x strsize=4k -qn 'bunyan$PID:::log-*{printf("%s", copyinstr(arg0))}' | bunyan

- issue 48: Dtrace support! The elevator pitch is you can watch all logging
from all Bunyan-using process with something like this:

dtrace -x strsize=4k -qn 'bunyan*:::log-*{printf("%d: %s: %s", pid, probefunc, copyinstr(arg0))}'

And this can include log levels *below* what the service is actually configured
to log. E.g. if the service is only logging at INFO level and you need to see
DEBUG log messages, with this you can. Obviously this only works on dtrace-y
platforms: Illumos derivatives of SunOS (e.g. SmartOS, OmniOS), Mac, FreeBSD.

Or get the bunyan CLI to render logs nicely:

dtrace -x strsize=4k -qn 'bunyan*:::log-*{printf("%s", copyinstr(arg0))}' | bunyan

See <https://github.com/trentm/node-bunyandtrace-support> for details. By
Bryan Cantrill.

- Export `bunyan.safeCycles()`. This may be useful for custom `type == "raw"`
streams that may do JSON stringification of log records themselves. Usage:

var str = JSON.stringify(rec, bunyan.safeCycles());

- [issue 49] Allow a `log.child()` to specify the level of inherited streams.
For example:

Before
var childLog = log.child({...});
childLog.level('debug');

After
var childLog = log.child({..., level: 'debug'});

- Improve the Bunyan CLI crash message to make it easier to provide relevant
details in a bug report.

- Fix a bug in the long-stack-trace error serialization added in 0.14.4. The
symptom:

bunyan0.14.4: .../node_modules/bunyan/lib/bunyan.js:1002
var ret = ex.stack || ex.toString();
^
TypeError: Cannot read property 'stack' of undefined
at getFullErrorStack (.../node_modules/bunyan/lib/bunyan.js:1002:15)
...