Introduce SALT_VERSION var

As we plan to move to salt 2017.7 and at the same time
we need to check 2016.3 as well (and upgrdae path), introduce
new var SALT_VERSION with default value 2016.3

Also update repo path to salt from mirror mirantis and clened up
commented hacks

Reelated: PROD-19373

Change-Id: I3c327aa4b6369750f5bdabe1b96cb52ab5770f03
diff --git a/tcp_tests/templates/virtual-mcp-ocata-dvr/_context-environment.yaml b/tcp_tests/templates/virtual-mcp-ocata-dvr/_context-environment.yaml
index 91f76f6..803068e 100644
--- a/tcp_tests/templates/virtual-mcp-ocata-dvr/_context-environment.yaml
+++ b/tcp_tests/templates/virtual-mcp-ocata-dvr/_context-environment.yaml
@@ -150,7 +150,7 @@
       - system.linux.system.repo.mcp.extra
       - system.linux.system.repo.mcp.apt_mirantis.openstack
       - system.linux.system.repo.mcp.apt_mirantis.ubuntu
-      - system.linux.system.repo.mcp.apt_mirantis.saltstack_2016_3
+      - system.linux.system.repo.mcp.apt_mirantis.saltstack
       interfaces:
         ens3:
           role: single_dhcp
@@ -167,7 +167,7 @@
       - system.linux.system.repo.mcp.extra
       - system.linux.system.repo.mcp.apt_mirantis.openstack
       - system.linux.system.repo.mcp.apt_mirantis.ubuntu
-      - system.linux.system.repo.mcp.apt_mirantis.saltstack_2016_3
+      - system.linux.system.repo.mcp.apt_mirantis.saltstack
       interfaces:
         ens3:
           role: single_dhcp