fix(HtmlTemplate): Now event parameter value can be used in the html template.

Author: Enuviel

AndroidSDK/src/com/leanplum/ActionContext.java

@@ -226,7 +226,7 @@ public String stringNamed(String name) {
     }
   }
 
-  private String fillTemplate(String value) {
+  public String fillTemplate(String value) {
     if (contextualValues == null || value == null || !value.contains("##")) {
       return value;
     }

AndroidSDK/src/com/leanplum/messagetemplates/HTMLOptions.java

@@ -170,8 +170,14 @@ private static String getTemplate(ActionContext context) {
     try {
       htmlString = (htmlTemplate.replace("##Vars##",
           ActionContext.mapToJsonObject(htmlArgs).toString()));
+      try {
+        htmlString = context.fillTemplate(htmlString);
+      } catch (Throwable ignored) {
+      }
     } catch (JSONException e) {
       Log.e("Leanplum", "Cannot convert map of arguments to JSON object.");
+    } catch (Throwable t) {
+      Log.e("Leanplum", "Cannot get html template.", t);
     }
     return htmlString.replace("\\/", "/");
   }