Create directory to move xci scripts from releng/jjb/xci

Create directory to move xci scripts from releng/jjb/xci

This change proposes creation of a folder named ci in releng-xci
in order to move the XCI scripts from Releng. The reason to name
the directory ci is that this directory has been in use by the
majority of OPNFV Projects and Releng either executes the scripts
directly or with the help of wrapper scripts that do not contain
project specific logic.

Scripts developed in releng/jjb/xci has too much XCI specific stuff
in them, making it difficult to keep the separation between
XCI framework and CI itself. Apart from that, having scripts
in Releng makes it troublesome to verify them properly.

Another importance of moving the scripts here is to ensure
these scripts can be used by other CI/automation tooling such
as Zuul in future. It is better to move the scripts now before
things get even more complicated to move.

Change-Id: Id22c2c2e09950b49a36a04a78208a3404de9c088
Signed-off-by: Fatih Degirmenci <fdegir@gmail.com>