Serial MPI-linked behavior fails when passing a config file in ADIOS constructor

Created by: williamfgc

Describe the bug Serial MPI-linked behavior fails when passing a config file in ADIOS constructor triggering MPI issue since MPI_Init is not called:

Profile Library *** The MPI_Comm_rank() function was called before MPI_INIT was invoked. 
*** This is disallowed by the MPI standard. 
*** Your MPI job will now abort. 
[login4:124071] Local abort before MPI_INIT completed completed successfully, but am not able to aggregate error messages, and not able to guarantee that all other processes were killed!

To Reproduce adios2::ADIOS adios("config.xml", true); will fail without MPI_Init

Expected behavior Run smoothly

Desktop (please complete the following information):

• OS/Platform: Ubuntu 18.04

Additional context Leftover MPI functionality should migrate to internal abstraction helper::Comm