Merge 58119316-centos-support to master

[#58119316]
Centos6 support documentation

This change adds the missed update to the documentation that points to
the centos6 repository.

[#58119316]
Merge 58119316-centos-support to master

[#58119316]
Only expose application through Tomcat

Previously, the Tomcat container symlinked the application root
directly to TOMCAT_HOME/webapps/ROOT.  This led to a problem where a
web application configured without a root servlet would expose the
filesystem of the application via the default servlet.  This change
fixes that issue by ensuring that only files and directories that are
uploaded by the user are mapped into the ROOT web application.

To make this change, the first implementation of an Application
abstraction has been created.  This initial implementation ensures
that only the originally upload application code is exposed and adds
utility methods for getting a component-specific directory and
determining paths relative to the application root.

[#59134502]
Rubocop fixes

Bad development practices led me to commit code without first running
the entire rake suite.  This fixes the problems introduced in the last
commit.

[#59134502]
Refactor Play application support and support Play 2.2

PlayAppPre22 and PlayAppPost22 encapsulate the Play-version specific
details of a Play application. PlayAppPre22Dist and PlayAppPre22Staged
represent the differences between Play 2.0/2.1 dist and a staged
applications, respectively.

BasePlayApp defines the interface to these classes and provides common
base methods.

PlayAppFactory isolates the using code from the concrete subclasses of
BasePlayApp.

Play version parsing and the naming requirements for the Play JAR are
both tightened up.

[#58432326]