Add support for upgrade install and repair install

[chris001]

I installed Alfresco 5.0a with this script, many months ago.
Now it's time to upgrade to alfresco community 5.0d (current version), with the latest version of all components.

It'd be great if this install script could do not only "install an empty new instance" as it currently does, but also "repair install, and upgrade install".

Detect the existing alfresco install and gracefully "upgrade install" in place, over all the various components (postgres, alfresco, java, solr, tomcat), without destroying the existing alfresco community instance, component configurations, or database.

For the components that are not present, the script installs them and applies default config to them.

For the components that are present, the script installs them without destroying existing config or data.

At the end of the script, if alfresco was working before, it is working now.

For components that were previously malfunctioning, the script would probably naturally fix it.

For example, suppose solr4 is broken with respect to alfresco, the script would install the latest solr4 version and the default working solr4 config.

[housni]

@chris001, how would we detect if something like solr4, for example, is broken?

I'm rewriting the install script in #17 and maybe I can accommodate this if I can figure out how, with your help.

[chris001]

@housni This page gives details on how to detect whether sol4 is broken, and steps to take to repair it.
http://stackoverflow.com/questions/28392504/how-to-fix-broken-solr4-in-alfresco-5-0-c-community-edition