cmd/tsr: read configuration file in main

This code is replicated through all subcommands. I'm not removing it
from there, yet.
collector: simplify Run
cmd/tsr: remove flags from the token subcommand
cmd/tsr: remove config from collector command

Also fix the call to collector.Run.
cmd/tsr: delete some dead code from token.go
cmd/tsr: remove flag definition from main
cmd/tsr/testdata: add another sample configuration file
cmd/tsr: add tsrCommand

This command will be used to register other commands. This way, we can
include the configuration file flag in all subcommands, and still
respect the commands framework, and the flags defined in subcommands.
api: improve RunServer function

Add some docs and stop receiving a map. Only the dry parameter matters
now.
cmd/tsr: remove config flag definition from apiCmd
cmd/tsr: use tsrCommand in main