Unittest - Make taskd the first argument of Task()

* The most common case is to bind a client to a server and not
customizing the location of the task binary
Unittest - Make client credentials available as a dictionary
Unittest - Helper code to easily parse tx.data
Unittest - Fix path to user tx.data
Merge pull request #12 in TM/task from ~UNODE/task:2.4.0 to 2.4.0

* commit '4a305d5e51c4cccbc99b9ed41476a82966891461':
  Unittest - Fix path to user tx.data
  Unittest - Helper code to easily parse tx.data
  Unittest - Make client credentials available as a dictionary
  Unittest - Make taskd the first argument of Task()