build: drop node v7, bump to 6.11 and 8.7

Author: sidorares

.travis.yml

@@ -9,11 +9,9 @@ matrix:
   include:
   - node_js: "4.8"
     env: LINT=0
-  - node_js: "6.10"
+  - node_js: "6.11"
     env: LINT=0
-  - node_js: "7.10"
-    env: LINT=0
-  - node_js: "8.4"
+  - node_js: "8.7"
     env: LINT=1
 
 cache:

appveyor.yml

@@ -7,9 +7,8 @@ environment:
   LINT: 0
 
   matrix:
-    - nodejs_version: "6.10"
-    - nodejs_version: "7.10"
-    - nodejs_version: "8.1"
+    - nodejs_version: "6.11"
+    - nodejs_version: "8.7"
       LINT: 1
 
 services: