Add install generator and support Rails 3 or 4

lib/generators/swagger_rails/install/templates/swagger.json

@@ -0,0 +1,45 @@
+{
+    "swagger": "2.0",
+    "info": {
+        "version": "0.0.0",
+        "title": "[Enter a description for your API here]",
+        "description": "The docs below are powered by the default swagger.json installed with swagger_rails. Please update it to describe your API. See here for the complete swagger spec - https://github.com/swagger-api/swagger-spec/blob/master/versions/2.0.md"
+    },
+    "paths": {
+        "/a/sample/resource": {
+            "post": {
+                "tags": [
+                  "a/sample/resource"
+                ],
+                "description": "Create a new sample resource",
+                "parameters": [
+                    {
+                        "name": "body",
+                        "in": "body",
+                        "schema": {
+                            "$ref": "#/definitions/CreateSampleResource"
+                        }
+                    }
+                ],
+                "responses": {
+                    "200": {
+                        "description": "Ok"
+                    }
+                }
+            }
+        }
+    },
+    "definitions": {
+        "CreateSampleResource": {
+            "properties": {
+                "name": {
+                    "type": "string"
+                },
+                "date_time": {
+                    "type": "string",
+                    "format": "date-time"
+                }
+            }
+        }
+    }
+}