Migration from previous plugin version

Change plugin versions from

    <properties>
        ...
        <play2.plugin.version>1.0.0-beta5</play2.plugin.version>
        <sbt-compiler.plugin.version>1.0.0-beta8</sbt-compiler.plugin.version>
    </properties>

to

    <properties>
        ...
        <play2.plugin.version>1.0.0-beta6</play2.plugin.version>
        <sbt-compiler.plugin.version>1.0.0-rc1</sbt-compiler.plugin.version>
    </properties>