Send program using vnc_api library in X-Conrail-Useragent header
in REST calls for identifying source of a change.

Change-Id: I81034621674d94b158a0c6302e11f1df0ac8a113
(cherry picked from commit e7fea63693bfedfd53deb708d2643283d52a1301)
Merge "Send program using vnc_api library in X-Conrail-Useragent header in REST calls for identifying source of a change." into R1.10