message: modified dataman doc to address latest changes
diff: -***************
  -DataMan for WAN
  -***************
  +******************************************
  +DataMan for Wide Area Network Data Staging
  +******************************************
  The DataMan engine is designed for data transfers over the wide area network. To use this engine, you can either specify it in your xml config file, with tag ``<engine type=DataMan>`` or set it in your application code:
  @@ -21,23 +21,33 @@ On the reader side you need to do instead:
  .. note::
  The DataMan engine currently does not support data staging within a cluster.
  -The DataMan engine does not accept any parameters. However, users are allowed to specify the following transport parameters:
  +The DataMan engine takes the following parameters:
  -1. **Library**: the underlying network / socket library used for data transfer.
  +1. **IPAddress**: the IP address of the host where the writer application runs.
  + This parameter is compulsory in wide area network data staging.
  -2. **IPAddress**: the IP address of the host where the writer application runs.
  +2. **Port**: the port on the writer host that will be used for data transfers.
  -3. **Port**: the port on the writer host that will be used for data transfers.
  +3. **Timeout**: the timeout in seconds to wait for every send / receive operation.
  + Packages not sent or received within this time are considered lost.
  -4. **Timeout**: the timeout in seconds to wait for every send / receive.
  +4. ``AlwaysProvideLatestTimestep``: Default **TRUE**.
  +AlwaysProvideLatestTimestep is a boolean parameter that affects what
  +of the available timesteps will be provided to the reader engine. If
  +AlwaysProvideLatestTimestep is **TRUE**, then if there are multiple
  +timesteps available to the reader, older timesteps will be skipped and
  +the reader will see only the newest available upon BeginStep.
  +This value is interpreted by only by the DataMan Reader engine.
  +If AlwaysProvideLatestTimestep is **FALSE**, then the reader engine
  +will be provided with the oldest step that has not been processed.
  -============= ================= ================================================
  +=============================== ================== ================================================
  **Key** **Value Format** **Default** and Examples
  -============= ================= ================================================
  - Library string **ZMQ**
  - IPAddress string **127.0.0.1**, 22.195.18.29
  - Port integer **12306**, 22000, 33000
  +=============================== ================== ================================================
  + IPAddress string **N/A**, 22.195.18.29
  + Port integer **50001**, 22000, 33000
  Timeout integer **5**, 10, 30
  -============= ================= ================================================
  + AlwaysProvideLatestTimestep boolean **TRUE**, false
  +=============================== ================== ================================================
  