File args

This pull request partially fixes one of the remaining incompatibilities with remote_syslog 1, by adding the ability to specify log files on the command line.

To do this we stash the path to the current working directory in an environment variable before daemonizing, as [suggested by the Godaemon maintainers](https://github.com/VividCortex/godaemon/pull/16#issuecomment-42988826).