Encapsulate jcli functionality into a JCLI class

Seperating the argument parsing and config file loading logic from the
main program logic will make writing tests easier. In theory.
... I should actually instantiate that class.

That would help.
Replace print statement with print function

Use the python3-style print function. Just because.
Print errors to stderr

Because linux.
Return appropriate exit status

Returning the appropriate exit status from your CLI tools makes
scripting, especially in *nix, much easier.  Non-zero means error. Check
out your local `sysexits.h` for more.
Merge remote-tracking branch 'upstream/master'

Conflicts:
	jcli
Merge remote-tracking branch 'upstream/master'
Quick fix
Merge pull request #3 from RWJMurphy/master

Linux-style return codes