Added option to run resource script on startup

[TheTechromancer]

I added an "-rc" argument which allows the user to specify a file containing commands to run (as if interactively) immediately upon startup.

Just a few basic changes:

1. Add "-rc" argument in main.go
2. Split DoWork() into an additional function for processing a single command, ProcessCommand()
3. Create ProcessResourceFile() function to read the script and execute its contents
4. Update readme

Thanks!