Update .travis.yml

.travis.yml

@@ -27,11 +27,13 @@ addons:
 before_install:
   # native dependencies
   - if [ $TRAVIS_OS_NAME == "linux" ]; then
+      sudo apt-add-repository ppa:snappy-dev/tools;
       sudo apt-get update -qq;
       sudo apt-get install -qq libxml2-dev;
       sudo apt-get install -qq libappindicator1;
       sudo apt-get install -qq rpm;
-      sudo apt install -qq snapcraft;
+      sudo apt-get install -qq snappy-tools;
+      sudo apt-get install -qq snapcraft;
     fi
 install:
   - git config --global core.autocrlf input