1.Changes were made keeping in mind to make use of automation in
the script tb.sh.
2.The changes made is easily be applied for layered build.
3.Removed layer env variable in localrc file as this guide is
about monolithic build.
4.Added new folder structure for centOS mirror output folder
5.New changes doesn't require to maintain three terminals.
Story: 2007580
Task: 39500
Change-Id: I76b915951cb6676da806ea0165d0ff51a1069209
Signed-off-by: Poornima <poornima.y.n@intel.com>
65f8a0abd1