Playing with master-slave

Start of work on master-slave stuff.  This is a checkpoint commit, I'm
going to write my own broadcaster (could use this but I want the
practice:
https://github.com/grafov/bcast/blob/master/bcast.go)
Add broadcast utility
Handle bcaster.Unjoin()
Add test for bcast
First master/slave is working.

I think I can do better than using generic interface{} channels
for the bcaster, but now it's demonstrated working.
Clarify stuff in --help

--listen and --control
Starting bidirectional communications

stats from slave back to master
also breaking out slave stuff into its own file.
Variable rename--this is a specific bcaster
make need broadcaster on reqPerSec channel

so need to make the interface generic
also removing cruft file slave.go--real one is in slave/slave.go
Send stats to master (rough draft)
Pretty sure bytes/recd is per clock sec, not req
logging cruft out
Merge branch 'master-slave' of github.com:kgoess/webserver-loadtest into master-slave
tweaking comment
have reqs/sec reflace counts from slaves

Moving messages to the requests/sec display channel from the
statsWinsController, which also controls the "duration" window,
into the barsWinsController, since it's all about counting requests/sec.
Since the barsWinsController is already getting messages from slaves,
now the requests/sec display reflects those too.
Add todo about count in the slave getting off
Handle HTTP errors in makeRequest

Moving that huge wadge of code out of requester() so that we
can return if the HTTP request failed, otherwise we hit
panics on undefined values.
Merge branch 'master-slave'

Conflicts:
	src/github.com/kgoess/webserver-loadtest/webserver-loadtest.go