chore(build): Switch target release to Java 8 and added travis CI config

.travis.yml

@@ -0,0 +1,18 @@
+language: java
+
+sudo: true
+
+script: 
+  - mvn clean package
+
+cache:
+  directories:
+    - $HOME/.m2
+jdk:
+  - openjdk11
+os:
+  - linux
+
+branches:
+  only:
+    - master

pom.xml

@@ -26,6 +26,7 @@
     <powermock.version>2.0.5</powermock.version>
     <h2.version>1.4.197</h2.version>
     <maven.javadoc.plugin.version>3.0.1</maven.javadoc.plugin.version>
+    <maven.compiler.release>8</maven.compiler.release>
   </properties>
 
   <modules>
@@ -62,7 +63,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.1</version>
+        <version>3.8.1</version>
         <configuration>
           <source>1.8</source>
           <target>1.8</target>