Many of the examples provided within documentation are using a single
dash for the command line arguments, but the telegraf executable
explicitly has two dashes.

There are also some inconsistencies with the ordering of the command
line argument examples.  I've ordered them so that the examples will
show: config, config-directory, input-filter, test

closes #1728

closes #656

Proper terminology and case. Exmaples for tags. Example output.

Make `go vet` happy.