Debug Update to Add a Password Scrubber and stdout style LogType

[luthermonson]

Most important part of this PR is the Scrub method added to the debug output to remove your password from the logs. To do this I just wrote a wrapper CloseWrite for FileType and to debug easier I wrote a LogType so decided to include it in the PR.

LogType uses go's log package and fakes a write/close to pass to the TeeReader and instead run a log.Print() on the contents which are normally written to file. This will show debug in your console while the command is running. @dougm would love your feedback as output is a bit messy but I didn't want to rock the boat too hard and kept some of file output like filename etc.

I additionally added a -debug to default to the stdout LogType method if no GOVC_DEBUG_PATH is not set so you don't magically write some log files without the govc user knowing (which happened to me)

[luthermonson]

ah crap i commited my build binary.. fixing

[luthermonson]

removed binary and force pushed, sorry about that.

[dougm]

Thanks @luthermonson , +1 to both scrubbing the password and having a stderr option for -debug. Just don't want to change the existing behavior, -debug alone should still default to using ~/.govmomi/debug

[luthermonson]

@dougm updated per feedback and rebased to one commit and force pushed

[luthermonson]

@dougm added readme update to deocument -debug since its looking like youre going to merge this.

[dougm]

Thanks @luthermonson , esp. for adding the long overdue docs. Keep in mind that debug also works with json (tags, content library, etc). Personally I always have:

% env | grep GOVC_DEBUG
GOVC_DEBUG_PATH_RUN=last
GOVC_DEBUG=true

And the I run $GOPATH/src/github.com/vmware/govmomi/scripts/debug-xmlformat.sh to view request/response logs.

I think it'd be awesome to have GOVC_DEBUG_PATH=- pretty-print the output as debug-xmlformat.sh does, but using Go's json + xml pretty printers. But that could be addressed in a separate PR.