Pass through return values from inside Docker to the Go wrapper

[vikrum]

If a call to Introspector fails or the query returns a failure, the Go wrapper should return a non-zero return value to the calling shell.

🤖 17:08:30 anglegrinder:introspector$ ./introspector asdfasdf
Usage: introspector.py [OPTIONS] COMMAND [ARGS]...
Try 'introspector.py --help' for help.

Error: No such command 'asdfasdf'.

🤖 17:08:40 anglegrinder:introspector$ echo $?
0

[vikrum]

802d66b