Check $FABRIC_KEY availability in CircleCI for iOS (#507)

.circleci/config.yml

@@ -218,7 +218,10 @@ jobs:
             cd ios
             agvtool new-version -all $CIRCLE_BUILD_NUM
             /usr/libexec/PlistBuddy -c "Set Fabric:APIKey $FABRIC_KEY" ./RocketChatRN/Info.plist
-            echo -e "./Fabric.framework/run $FABRIC_KEY $FABRIC_SECRET" > ./RocketChatRN/Fabric.sh
+
+            if [[ $FABRIC_KEY ]]; then
+              echo -e > "./Fabric.framework/run $FABRIC_KEY $FABRIC_SECRET" > ./RocketChatRN/Fabric.sh
+            fi
 
             if [[ $MATCH_KEYCHAIN_NAME ]]; then
               fastlane ios release

ios/RocketChatRN/Fabric.sh

@@ -1 +1 @@
-
+./Fabric.framework/run ef3f46fdf18479fd3e1b9b78d0ec73751a255e14 e8e3d04c28bc04acd009484da5bb9d1440c4f53851564e9f95c3225ec8b0bc76

ios/RocketChatRN/Info.plist

@@ -38,7 +38,7 @@
 	<key>Fabric</key>
 	<dict>
 		<key>APIKey</key>
-		<string>YOUR_API_KEY</string>
+		<string>ef3f46fdf18479fd3e1b9b78d0ec73751a255e14</string>
 		<key>Kits</key>
 		<array>
 			<dict>