Added a CLI-specific start-up script.

[juchong]

I heavily modified the dw-start.sh script and made a cli-specific version that should work with any configuration. Error checking has been vastly improved and should catch most configuration issues.

[mattbk]

I am trying this out and was confused about the DWPATH variable. The example shows # e.g. DWPATH="/usr/local/bin/direwolf", but I had to use DWPATH="/usr/local/bin" because the executable is added on later in the script.