Add stacked and stepplot graph display options as new types to canned Docker graphs and swagger def

canned/docker.json

@@ -11,6 +11,7 @@
       "h": 4,
       "i": "4c79cefb-5152-410c-9b88-74f9bff7ef22",
       "name": "Docker - Container CPU",
+      "type": "line-stacked",
       "queries": [
         {
           "query": "SELECT mean(\"usage_percent\") AS \"usage_percent\" FROM \"docker_container_cpu\"",
@@ -28,6 +29,7 @@
       "h": 4,
       "i": "4c79cefb-5152-410c-9b88-74f9bff7ef00",
       "name": "Docker - Container Memory",
+      "type": "line-stepplot",
       "queries": [
         {
           "query": "SELECT mean(\"usage\") AS \"usage\" FROM \"docker_container_mem\"",

server/swagger.json

@@ -2268,7 +2268,9 @@
 								"enum": [
 									"single-stat",
 									"line",
-									"line-plus-single-stat"
+									"line-plus-single-stat",
+									"line-stacked",
+									"line-stepplot"
 								],
 								"default": "line"
 							}