Reduce the number of test runs on Travis

* `fastboot-1.2`: was essentially the same as `ember-lts-3.8` because `fastboot` in package.json is already using `^1.2.1`
* `ember-default`: was the same as `stage: test`
* `ember-lts-2.12`, `ember-lts-2.16`: seems reasonable to limit ember 2.x tests to the oldest supported and the latest LTS versions

Author: cvx

.travis.yml

@@ -47,17 +47,13 @@ jobs:
 
     - stage: versioned tests
       env: EMBER_TRY_SCENARIO=ember-lts-2.8
-    - env: EMBER_TRY_SCENARIO=ember-lts-2.12
-    - env: EMBER_TRY_SCENARIO=ember-lts-2.16
     - env: EMBER_TRY_SCENARIO=ember-lts-2.18
     - env: EMBER_TRY_SCENARIO=ember-lts-3.4
     - env: EMBER_TRY_SCENARIO=ember-lts-3.8
-    - env: EMBER_TRY_SCENARIO=fastboot-1.2
     - env: EMBER_TRY_SCENARIO=fastboot-2.0
     - env: EMBER_TRY_SCENARIO=ember-release
     - env: EMBER_TRY_SCENARIO=ember-beta
     - env: EMBER_TRY_SCENARIO=ember-canary
-    - env: EMBER_TRY_SCENARIO=ember-default
 
     - stage: deploy
       if: (branch = master OR tag IS present) AND type = push

config/ember-try.js

@@ -28,22 +28,6 @@ module.exports = function() {
             }
           }
         },
-        {
-          name: 'ember-lts-2.12',
-          npm: {
-            devDependencies: {
-              'ember-source': '~2.12.0'
-            }
-          }
-        },
-        {
-          name: 'ember-lts-2.16',
-          npm: {
-            devDependencies: {
-              'ember-source': '~2.16.0'
-            }
-          }
-        },
         {
           name: 'ember-lts-2.18',
           npm: {
@@ -68,15 +52,6 @@ module.exports = function() {
             }
           }
         },
-        {
-          name: 'fastboot-1.2',
-          npm: {
-            devDependencies: {
-              'ember-source': '~3.8.0',
-              'fastboot': '^1.2.1'
-            }
-          }
-        },
         {
           name: 'fastboot-2.0',
           npm: {
@@ -109,12 +84,6 @@ module.exports = function() {
               'ember-source': urls[2]
             }
           }
-        },
-        {
-          name: 'ember-default',
-          npm: {
-            devDependencies: {}
-          }
         }
       ]
     };