Document Registry interface.
Add link to docs, fix example.
Fix comment.
Pedantic.
Update for the new interface.
Merge branch 'master' of git://github.com/AlekSi/go-metrics
Interface checks all over.

Also some pedantry.
don't build syslog on windows
Merge pull request #8 from inconshreveable/master

Add build constraint for syslog so that it doesn't build on windows
Clarify in the README that the "outputs" do not return