Upgrade Java version from 1.6 to 1.8 in javadoc and enforcer Maven plugins

Author: gslowikowski

pom.xml

@@ -246,7 +246,7 @@ under the License.
                     <artifactId>maven-javadoc-plugin</artifactId>
                     <version>3.0.1</version>
                     <configuration>
-                        <source>1.6</source>
+                        <source>1.8</source>
                         <detectJavaApiLink>false</detectJavaApiLink>
                         <subpackages>org.scoverage.plugin</subpackages>
                         <links>
@@ -540,8 +540,8 @@ under the License.
                         <configuration>
                             <rules>
                                 <requireJavaVersion>
-                                    <version>1.6</version>
-                                    <message>Java 1.6 or later required.</message>
+                                    <version>1.8</version>
+                                    <message>Java 1.8 or later required.</message>
                                 </requireJavaVersion>
                             </rules>
                         </configuration>