prune packages at both folders before trying to install

.travis.yml

@@ -21,6 +21,8 @@ cache:
     - node_modules
 
 install:
+  - npm prune
+  - cd app && npm prune && cd ..
   - npm install
 
 script:

appveyor.yml

@@ -27,6 +27,8 @@ install:
   - ps: $fileContent += "`n-----END RSA PRIVATE KEY-----`n"
   - ps: Set-Content c:\users\appveyor\.ssh\id_rsa $fileContent
   - git submodule update --init --recursive
+  - npm prune
+  - cd app && npm prune && cd ..
   - npm install
 
 build_script: