Use return code to track command status

[protohuf]

Using a string to track command success doesn't seem to work in all circumstances. Using the return code directly instead works fine.

In a situation where AMP is not ready to respond to the PATCH request, using result.stdout.find("command terminated") == -1 will fail immediately (no retries). Using return code works:

TASK [roc-load : load roc models file] ********************************************************************************************************************************************************************************************************
FAILED - RETRYING: [node1]: load roc models file (5 retries left).
FAILED - RETRYING: [node1]: load roc models file (4 retries left).
FAILED - RETRYING: [node1]: load roc models file (3 retries left).
FAILED - RETRYING: [node1]: load roc models file (2 retries left).
changed: [node1]