ECP VELOC (#8581)

* kvtree package file

* MPI is default on

* proper mpi compiler

* rankstr package

* better rankstr description

* typo

* redset package

* shuffile package

* er package

* axl package

* proper pythor

* mpi is default on

* alpha releases and master versions

* veloc package with boost headers dep

* cmake version

* added C++11 requirement

* flake8

* flake8

* ecp tag

* axl: better async api option handling

* veloc package description

* prettier args list

* C++11 flag handler

* v1.0 of veloc