Merge branch 'VDIScalability' into 'master'

Vdi scalability

Recent improvements in config limits has increased number of VDIs per VM to 255.

Changes are made in VDI Scalability TC in xenrt to accomodate 255 VDIs for both linux and windows VMs.

Jobs Run: Passed job(Linux VM):1188254 Failed job because of product issue(Windows VM): 1189734(Product issue CA-184556)

-Akash

See merge request !3

diff --cc exec/xenrt/config.py
Simple merge

diff --cc exec/xenrt/lib/xenserver/guest.py
Simple merge