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**Description**
As MPI can not be inited twice in one same process (by py and c)
Also, MPI env initialized by mpi4py can not be reused in C env

To avoid MPI init issue introduced from mpi4py, rewrite gen_ibstat_file function to generate ibstat file leveraged by pssh

**Major Revision**
- Rewrite gen_ibstat_file function to generate ibstat file leveraged by pssh

**Minor Revision**
- Remove mpi4py dependency

Tested the functionality of topo-aware on 36 nodes cluster

An enhancement for topo-aware IB performance validation #373.
This PR will auto-generate a required ibstate file `ib_traffic_topo_aware_ibstat.txt` which is used as input to build a graph.

* Support topo-aware IB performance validation

Add a new pattern `topo-aware`, so the user can run IB performance
test based on VM's topology information. This way, the user can
validate the IB performance across VM pairs with different distance
as a quick test instead of pair-wise test.

To run with topo-aware pattern, user needs to specify three required
(and two optional) parameters in YAML config file:
--pattern	topo-aware
--ibstat	path to ibstat output
--ibnetdiscover	path to ibnetdiscover output
--min_dist	minimum distance of VM pairs (optional, default 2)
--max_dist	maximum distance of VM pairs (optional, default 6)

The newly added topo_aware module then parses the topology
information, builds a graph, and generates the VM pairs with
the specified distance (# hops).

The specified IB test will then be running across these
generated VM pairs.
Signed-off-by: Jie Zhang <jessezhang1010@gmail.com>

* Add description about topology aware ib traffic tests
Signed-off-by: Jie Zhang <jessezhang1010@gmail.com>

* Add unit test to verify generated topology aware config file

This commit adds unit test to verify the generated topology aware
config file is correct. To do so, four new data files are added in
order to invoke gen_topo_aware_config function to generate topology
aware config file, then compares it with the expected config file.
Signed-off-by: Jie Zhang <jessezhang1010@gmail.com>

* Fix lint issue on Azure pipeline
Signed-off-by: Jie Zhang <jessezhang1010@gmail.com>