chore: Add scripts to automate playstore release (fossasia#278)

* chore: add scripts to automate playstore release

* chore: Add encrypted key

Author: nikit19

Diff for: .gitignore

@@ -130,3 +130,7 @@ fabric.properties
 ### AndroidStudio Patch ###
 
 !/gradle/wrapper/gradle-wrapper.jar
+
+fastlane.json
+key.jks
+secrets.tar

Diff for: .travis.yml

@@ -21,4 +21,5 @@ install:
 script:
   - ./gradlew build
 after_success:
+    - bash scripts/prep-key.sh
     - bash scripts/update-apk.sh

Diff for: scripts/prep-key.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+set -e
+
+export DEPLOY_BRANCH=${DEPLOY_BRANCH:-master}
+
+if [ "$TRAVIS_PULL_REQUEST" != "false" -o "$TRAVIS_REPO_SLUG" != "fossasia/open-event-android" -o "$TRAVIS_BRANCH" != "$DEPLOY_BRANCH" ]; then
+    echo "We decrypt key only for pushes to the master branch and not PRs. So, skip."
+    exit 0
+fi
+
+# Decrypt keys
+openssl aes-256-cbc -K $encrypted_59a1db41ee4d_key -iv $encrypted_59a1db41ee4d_iv -in ./scripts/secrets.tar.enc -out ./scripts/secrets.tar -d
+tar xvf ./scripts/secrets.tar -C scripts/

Diff for: scripts/secrets.tar.enc

@@ -47,6 +47,15 @@ if [ "$TRAVIS_BRANCH" == "$DEPLOY_BRANCH" ]; then
 	done
 fi
 
+# Signing Apps
+
+if [ "$TRAVIS_BRANCH" == "$PUBLISH_BRANCH" ]; then
+    echo "Push to master branch detected, signing the app..."
+    cp app-release-unsigned.apk app-release-unaligned.apk
+	jarsigner -verbose -tsa http://timestamp.comodoca.com/rfc3161 -sigalg SHA1withRSA -digestalg SHA1 -keystore ../scripts/key.jks -storepass $STORE_PASS -keypass $KEY_PASS app-release-unaligned.apk $ALIAS
+	${ANDROID_HOME}/build-tools/27.0.3/zipalign -v -p 4 app-release-unaligned.apk app-release.apk
+fi
+
 # Create a new branch that will contains only latest apk
 git checkout --orphan temporary
 
@@ -61,3 +70,12 @@ git branch -m apk
 
 # Force push to origin since histories are unrelated
 git push origin apk --force --quiet > /dev/null
+
+# Publish App to Play Store
+if [ "$TRAVIS_BRANCH" != "$PUBLISH_BRANCH" ]; then
+    echo "We publish apk only for changes in master branch. So, let's skip this shall we ? :)"
+    exit 0
+fi
+
+gem install fastlane
+fastlane supply --apk test-app-release.apk --track alpha --json_key ../scripts/fastlane.json --package_name $PACKAGE_NAME