DL-50: Add coveralls plugin to the build and enable it on github page

Author: Sijie Guo <sijie@apache.org>

Reviewers: Franck Cuny <franck.cuny@gmail.com>

Closes #23 from sijie/sijie/add_coveralls_plugin
diff --git a/README.md b/README.md
index 0ef47c8..d3c3a7c 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,5 @@
 [![Build Status](https://travis-ci.org/apache/incubator-distributedlog.svg?branch=master)](https://travis-ci.org/apache/incubator-distributedlog)
+[![Coverage Status](https://coveralls.io/repos/github/apache/incubator-distributedlog/badge.svg?branch=master)](https://coveralls.io/github/apache/incubator-distributedlog?branch=master)
 
 ## Overview
 
diff --git a/pom.xml b/pom.xml
index fc90d81..f8e757d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -189,6 +189,12 @@
           </excludes>
         </configuration>
       </plugin>
+      <!-- Report jacoco coverage to coveralls.io -->
+      <plugin>
+        <groupId>org.eluder.coveralls</groupId>
+        <artifactId>coveralls-maven-plugin</artifactId>
+        <version>4.1.0</version>
+      </plugin>
     </plugins>
   </build>
   <repositories>