Another webapp plugin for sbt

To build this code, get and install SBT from
    https://github.com/sbt/sbt

Get and install these plugins before building:
    https://github.com/ritschwumm/xsbt-util
    https://github.com/ritschwumm/xsbt-classpath

Build and publish the plugin:
    git clone git@github.com:ritschwumm/xsbt-webapp.git
    cd xsbt-webapp
    sbt publish-local

Add the plugin to your project in project/plugins.sbt:
    addSbtPlugin("de.djini" % "xsbt-webapp" % <version>)

Run the webapp task to get a web application directory.

Then run the webappWar task to get a zipped up war file.

Resource libraries can be added like this:

    libraryDependencies += "com.test" % "foobar" % "0.1.0" % "webapp"

To deploy the webapp to a servlet container e.g. tomcat, include something like this in the build.sbt:

    webappDeployName    := "ROOT"

    webappDeployBase    :=
            Option(System getenv "CATALINA_HOME")
            .map        (file)
            .map        { _ / "webapps" }
            .filter     { _.isDirectory }

Then run the webappDeploy task; it will first delete $CATALINA_HOME/webapps/ROOT
and $CATALINA_HOME/webapps/ROOT.war and then copy an exploded webpp directory to
$CATALINA_HOME/webapps/ROOT .