[CHORE] Added campaign field on generating link

Author: Renemari Padillo

src/android/io/branch/BranchSDK.java

@@ -459,6 +459,9 @@ private BranchLinkProperties createLinkProperties(JSONObject options, JSONObject
         if (options.has("stage")) {
             linkProperties.setStage(options.getString("stage"));
         }
+        if (options.has("campaign")) {
+            linkProperties.setCampaign(options.getString("campaign"));
+        }
         if (options.has("duration")) {
             linkProperties.setDuration(options.getInt("duration"));
         }

src/ios/BranchSDK.m

@@ -454,6 +454,9 @@ - (void)generateShortUrl:(CDVInvokedUrlCommand*)command
         else if ([key isEqualToString:@"stage"]) {
             props.stage = [arg1 objectForKey:key];
         }
+        else if ([key isEqualToString:@"campaign"]) {
+            props.campaign = [arg1 objectForKey:key];
+        }
         else if ([key isEqualToString:@"alias"]) {
             props.alias = [arg1 objectForKey:key];
         }