Update all usage of "server" lp to "nw-lp"

This change is made for consistency across all configuration files
and workload generators in core CODES. Where older models and versions
of CODES utilized the "server" identifier to specify the number of
server LPs per modelnet group repetition, newer models and
configurations utilized the less paradigm specific "nw-lp" identifier.

This shift slightly fractured the codebase and led to confusion when
running similar/same configurations across different network models.

Specifically, this change converts all usage of the "server" identifier
to the "nw-lp" identifier. All tests, existing default configuration
files, and models have been updated to use the "nw-lp" identifier for
the workload server LPs. Some docs and readmes have been updated as well
to no longer instruct new users to use the "server" identifier.

Adding first pass of dragonfly custom model: routings (adaptive, progressive adaptive, minimal, non-minimal) should be functional with DF traces, need to update for making optimistic mode functional

Adding sampling examples in synthetic workload test program, fixing a reverse handler bug in synthetic workload test

Changing the hash function to bj_hash_little2, more additions to the MPI Sim layer operation matching

NOTE: caused an event size bump - you may need to update config files

Updated congestion control in dragonfly: now messages are saved in a waiting list at the routers in case of buffer overflows

Adding group level mapping in the dragonfly: multiple routers can now be specified in the config file

Adding further updates to the dragonfly routing (statistics for adaptive routing updated, conditions for queue congestion sensing updated)

1) Adding dragonfly adaptive and prog-adaptive routing algorithms--- still testing with more workloads and crosschecking the computation 2) Two bug fixes in credit-based flow control

- "modelnet" parameter in cfg is now a no-op
- "modelnet_order" parameter in cfg is required,
  listing order in which networks are indexed to
  the model
- modified "model_net_set_params" signature
- updated tests to use the new interface

Updates to modelnet (1) Updated the mapping configuration for dragonfly (the mapping now distributes the routers equally on all the PES.  The old dragonly mapping configuration was placing the routers on a single PE which was causing congestion on that PE leading to slow model performance in parallel ) (2) Updated 'make check' to handle dragonfly and torus test cases as well (3) Remove the num_servers argument from model-net test case, the number of servers are now calculated from the config file (4) Placing the ross mapping parameters in the codes mapping file

Adding dragonfly network model with codes, model-net-test case run time parameters are updated (see README_MN_TEST.txt for details)