Deploy scripts should fail on errors, update root swift version to 4.2

.swift-version

@@ -1 +1 @@
-4.0
+4.2

scripts/deploy.sh

@@ -1,7 +1,4 @@
-if [ -z $BINTRAY_USER ]; then
-  echo "Must define BINTRAY_USER and BINTRAY_KEY env var before deploying. See https://github.com/ionic-team/capacitor/blob/master/.github/CONTRIBUTING.md"
-  exit 1
-fi
+set -e
 
 LERNA_JSON=`cat lerna.json`;
 export LERNA_VERSION="$(node -pe "JSON.parse(\`$LERNA_JSON\`)['version']")"

scripts/deploy/pods.sh

@@ -1,3 +1,5 @@
+set -e
+
 echo "Deploying iOS Pods v$POD_VERSION"
 
 # Publish CapacitorCordova first

scripts/generate.sh

@@ -1,3 +1,5 @@
+set -e
+
 LERNA_JSON=`cat lerna.json`;
 export LERNA_VERSION="$(node -pe "JSON.parse(\`$LERNA_JSON\`)['version']")"
 

scripts/prerelease.sh

@@ -2,6 +2,11 @@ set -e
 
 [ -z "$ANDROID_HOME" ] && echo "ANDROID_HOME is not set. Please set it before running this script." && exit 1;
 
+if [ -z $BINTRAY_USER ]; then
+  echo "Must define BINTRAY_USER and BINTRAY_KEY env var before deploying. See https://github.com/ionic-team/capacitor/blob/master/.github/CONTRIBUTING.md"
+  exit 1
+fi
+
 # Verify pods are good
 pod spec lint --allow-warnings Capacitor.podspec
 pod spec lint --allow-warnings CapacitorCordova.podspec