ENHANCEMENT: Add fabric routes to BGP & VxLAN labs

[bingbucks]

Possible enhancement for the VxLAN lab, although not necessary.

The /30's between the leafs & spines are not advertised anywhere, so if someone was on Leaf1 and tried to execute:
leaf1()# ping 172.16.0.56 there is no route back from Leaf3 or Leaf4 (the owner's of shared loopback1) to the interface that was used for the source IP address in the outgoing Ping Request (which will be one of the /30's from Leaf1 - Eth2 or Eth3).

Of course, someone could execute:
leaf1()# ping 172.16.0.56 source 172.16.0.34 to take care of the source IP address of the Ping Request, but then due to ECMP hashing the Ping Reply may never come back to Leaf1 but to Leaf2, which to the user my look like a failure.

While there are no loopback1's in the BGP (L3LS) lab, the /30's are not advertised either. Perhaps the same enhancement could be added.

[bingbucks]

Configlet updates needed in:

• Leaf1-BGP-Lab
• Leaf1-VXLAN-Lab
• Leaf2-BGP-Lab
• Leaf2-VXLAN-Lab
• Leaf3-BGP-Lab
• Leaf3-VXLAN-Lab
• Leaf4-BGP-LAB-Full
• Leaf4-VXLAN-Lab
• Spine1-BGP-Lab
• Spine2-BGP-Lab