Add rising bollard exception to barriers for car profile.

This handles `barrier=bollard` with `bollard=rising`, by making an
exception to the barrier whitelist. Barriers tagged as such do no longer
require an explicit access tag.

This also adds corresponding tests, check this out:

    cucumber --tags @barrier

References:

- http://wiki.openstreetmap.org/wiki/Tag:barrier%3Dbollard
- http://wiki.openstreetmap.org/wiki/Key:bollard
- https://github.com/Project-OSRM/osrm-backend/issues/1616

features/car/barrier.feature

@@ -37,3 +37,10 @@ Feature: Car - Barriers
             | wall         | no            |       |
             | wall         | private       |       |
             | wall         | agricultural  |       |
+
+    Scenario: Car - Rising bollard exception for barriers
+        Then routability should be
+            | node/barrier | node/bollard  | bothw |
+            | bollard      |               |       |
+            | bollard      | rising        | x     |
+            | bollard      | removable     |       |

profiles/car.lua

@@ -195,7 +195,11 @@ function node_function (node, result)
   else
     local barrier = node:get_value_by_key("barrier")
     if barrier and "" ~= barrier then
-      if not barrier_whitelist[barrier] then
+      --  make an exception for rising bollard barriers
+      local bollard = node:get_value_by_key("bollard")
+      local rising_bollard = bollard and "rising" == bollard
+
+      if not barrier_whitelist[barrier] and not rising_bollard then
         result.barrier = true
       end
     end