Still need to deal with the use case of not passing a block; blocks
should not be required, it should be okay to invoke and just wait for
the complete attribute to be true. You'll miss out on error messages but
eh, maybe those should be return values.
Adds error checking and some helpful messaging in the event of an error.
In the event of a failed transfer the module exits immediately, but in
success, I'm still hanging around for several seconds after. Not a deal
breaker but can be annoying.
Also, need to implement a read as well as a write and store it as loot,
to be actually useful for most TFTP checking.
Tod Beardsley