Make site deployment consistent

[khmarbaise]

Currently we make a difference between mono module project and non mono module projects.
We should make it consistent and only use one way to go.
This means from my point of view:

• Use configuration for maven-scm-publish-plugin like this:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-scm-publish-plugin</artifactId>
  <version>3.0.0</version>
  <configuration>
    <pubScmUrl>${project.scm.developerConnection}</pubScmUrl>
    <scmBranch>gh-pages</scmBranch>
    <content>${project.build.directory}/staging</content>
  </configuration>
..
</plugin>

• Also we should use configuration during the release like this:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-release-plugin</artifactId>
  <version>2.5.3</version>
  <configuration>
    <arguments>${arguments}</arguments>
    <goals>deploy site site:stage scm-publish:publish-scm</goals>
    <autoVersionSubmodules>true</autoVersionSubmodules>
   </configuration>
</plugin>

• This would result in having always the same path to go no differences

Consequences

• every project has to define a property like this: <scmpublish.content>target/staging/${project.artifactId}</scmpublish.content>
• every project has to define the distributionManagement like this:

  <distributionManagement>
    <site>
      <id>github</id>
      <url>scm:git:ssh://git@github.com/mojohaus/<repository>.git</url>
    </site>
  </distributionManagement>

[hboutemy]

@khmarbaise on the second point (automatic site publish during release): this can't work for multi-module builds, because such build require site:stage during initial build then another build to do the scm-publish (from staging area)

this is why there is the optimisation on mono-module builds, that don't require this staging extra step...

I can't force you to prefer one single way to run site, then avoiding the mono-module optimisation, but I must avoid failure during release