tx client misbehaviour: tx exits with code 0 even on error

[Mi605]

Scope:

• TX Client, version=1.6.5

Focus:

• tx client exit codes

Issue:

• tx client exits with exit code 0 when it shouldn't. An exit code of 0 (zero) means on linux the program has done its tasks without error.
  Despite of this, tx client returns 0 even if it failed to finish its task properly.

Expected behaviour:

• tx client mustn't return 0 (zero) in case of the requested task wasn't done.
  In case the command can't finish its task for some reason, it is expected to
  return at least a value of 1 (one), or a separate number other than zero for each type of error.

Example:

$ tx pull -s
# Getting info about resources

test-project.test-files - Resource test-project.test-files does not exist
[##############################] (1 / 1)

$ echo $?
0

[Mi605]

Additional information:
On some other error conditions tx client returns 1 (one) properly.
Re-checking the error described in #173, this time I counterchecked with echo $? after execution, and this command came properly back with 1 after the transmission of one of the files failed. So obviously only some of the tx commands are subject of not returning proper exit status after execution of the task failed.