more build fixes:

ikreymer · ikreymer · commit 8a590c7cfc17 · 2019-07-31T17:33:18.000-07:00
- use later osx image for travis
- use only appimage build in linux
diff --git a/.travis.yml b/.travis.yml
@@ -5,6 +5,7 @@ matrix:
       node_js:
         - "10"
     - os: osx
+      osx_image: xcode10.2
       language: node_js
       node_js:
         - "10"
diff --git a/package.json b/package.json
@@ -54,7 +54,10 @@
       "target": "dmg"
     },
     "linux": {
-      "category": "Archiving;Utility;"
+      "category": "Archiving;Utility;",
+      "target": [
+        "AppImage"
+      ]
     },
     "win": {
       "target": "portable"
