runCommand -package:wai-app-static -package:libmpd -package:io-streams -package:shake-plus -package:beam-migrate -package:hledger is:exact -package:pandoc-plot -package:graphviz -package:process -package:cabal-install -package:github-release -package:options -package:lambdabot-core

Run a Command.
Given a list of command/action pairs, prompt the user to choose a command using dmenu and return the corresponding action.