Update .travis.yaml to download ballerina installer in Travis Builds

.travis.yml

@@ -8,14 +8,16 @@ services:
 cache:
   directories:
     - .autoconf
-    - $HOME/.m2
+    - ${HOME}/.m2
 before_install:
+  - wget https://product-dist.ballerina.io/downloads/0.990.3/ballerina-linux-installer-x64-0.990.3.deb
+  - sudo dpkg -i ballerina*.deb
   - wget https://wso2.org/jenkins/view/cellery/job/cellery/job/sdk/lastSuccessfulBuild/artifact/installers/ubuntu-x64/target/*zip*/target.zip
   - unzip target.zip
-  - sudo dpkg -i target/*.deb
+  - sudo dpkg -i target/cellery*.deb
   - npm i -g npm
-  - mkdir -p $HOME/gopath/src/github.com/cellery-io
-  - mv ${TRAVIS_BUILD_DIR} $GOPATH/src/github.com/cellery-io/samples
-  - export TRAVIS_BUILD_DIR=$HOME/gopath/src/github.com/cellery-io/samples
-  - cd $HOME/gopath/src/github.com/cellery-io/samples
+  - mkdir -p ${GOPATH}/src/github.com/cellery-io
+  - mv ${TRAVIS_BUILD_DIR} ${GOPATH}/src/github.com/cellery-io/samples
+  - export TRAVIS_BUILD_DIR=${GOPATH}/src/github.com/cellery-io/samples
+  - cd ${GOPATH}/src/github.com/cellery-io/samples
 script: make clean check-style build docker cellery-build