fixes #358 by updating to Java8 (#359)

Author: mivola

.travis.yml

@@ -36,7 +36,7 @@ after_script:
 # http://www.webupd8.org/2017/06/why-oracle-java-7-and-6-installers-no.html
 # - oraclejdk8 is not supported anymore.
 jdk:
- - openjdk7
+ - openjdk8
 cache:
   directories:
   - $HOME/.m2/repository

pom.xml

@@ -43,8 +43,8 @@
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-    <maven.compiler.source>1.7</maven.compiler.source>
-    <maven.compiler.target>1.7</maven.compiler.target>
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
     <maven.compiler.showDeprecation>true</maven.compiler.showDeprecation>
     <maven.compiler.showWarnings>true</maven.compiler.showWarnings>