add lts-3.4 and lts-3.8 to ember-try matrix

Author: xomaczar

.travis.yml

@@ -21,6 +21,7 @@ env:
   - EMBER_TRY_SCENARIO=ember-lts-2.12
   - EMBER_TRY_SCENARIO=ember-lts-2.18
   - EMBER_TRY_SCENARIO=ember-lts-3.4
+  - EMBER_TRY_SCENARIO=ember-lts-3.8
   - EMBER_TRY_SCENARIO=ember-release
   - EMBER_TRY_SCENARIO=ember-beta
   - EMBER_TRY_SCENARIO=ember-canary

config/ember-try.js

@@ -35,6 +35,22 @@ module.exports = {
         }
       }
     },
+    {
+      name: 'ember-lts-3.4',
+      npm: {
+        devDependencies: {
+          'ember-source': '~3.4.0'
+        }
+      }
+    },
+    {
+      name: 'ember-lts-3.8',
+      npm: {
+        devDependencies: {
+          'ember-source': '~3.8.0'
+        }
+      }
+    },
     {
       name: 'ember-release',
       bower: {