Remove Travis configuration and add no-return-await TS lint rule (#33)

* Add no-return-await TS lint rule

* Remove Travis configuration

.travis.yml

@@ -1,5 +0,0 @@
-language: node_js
-sudo: false
-node_js:
-  - "6"
-  - "8"

tslint.json

@@ -43,14 +43,15 @@
                 "variable-declaration": "onespace"
             }
         ],
-        "no-internal-module": true,
-        "no-trailing-whitespace": true,
-        "no-inferrable-types": [true],
-        "no-null-keyword": true,
-        "prefer-const": true,
-        "no-switch-case-fall-through": true,
-        "triple-equals": true,
         "jsdoc-format": true,
-        "max-classes-per-file": [true, 1]
+        "max-classes-per-file": [true, 1],
+        "no-inferrable-types": [true],
+        "no-internal-module": true,
+        "no-null-keyword": true,
+        "no-return-await": true,
+        "no-switch-case-fall-through": true,
+        "no-trailing-whitespace": true,
+        "prefer-const": true,
+        "triple-equals": true
     }
 }