Issue #158 bump central-publishing-maven-plugin to 0.8.0

The Central Portal API now returns a 'warnings' field in the deployment
response which the strict Jackson model in plugin 0.6.0 cannot parse,
failing the publish after a successful upload with
UnrecognizedPropertyException. 0.8.0 knows the new response fields.

Author: simbo1905

pom.xml

@@ -208,7 +208,7 @@
                     <plugin>
                         <groupId>org.sonatype.central</groupId>
                         <artifactId>central-publishing-maven-plugin</artifactId>
-                        <version>0.6.0</version>
+                        <version>0.8.0</version>
                         <extensions>true</extensions>
                         <configuration>
                             <publishingServerId>central</publishingServerId>