Implemented Vault integration in k-s-a

@viktor.popov, @alexander.holodov & @damyan.mitev: Can you please review these changes?

Gopkg.toml

 [[constraint]]
-  branch = "master"
+  branch = "107-Vault_integration"
   name = "code.vereign.com/code/viam-apis"
 
 [[constraint]]