Add a Zanata overlay zip submodule.

Pull Request: https://github.com/zanata/zanata-server/pull/637
Squashed commit of the following:

commit ac46d8051275c9738db875dd29d7f4c1a43b85b1
Author: Carlos A. Munoz <camunoz@redhat.com>
Date:   Mon Dec 15 15:57:40 2014 +1000

    Minor zanata installer changes

    - Reverted to latest mysql driver info
    - Added a few log lines to know what's happening

commit 4110de2921804b5e37874b65385986b1b8878790
Author: Carlos A. Munoz <camunoz@redhat.com>
Date:   Wed Dec 10 16:54:00 2014 +1000

    More review changes:

    Fix issues with the windows script for installation
    Change wording and correct spelling for installer messages.

commit fc5daf1bf29b484e5a4e41c7d71f728f4c2c2b6b
Author: Carlos A. Munoz <camunoz@redhat.com>
Date:   Mon Dec 8 16:19:19 2014 +1000

    Make sure the installation process is repeatable if there is a failure.

    Also, downgraded the mysql driver version as the one used before did not deploy on wildfly.

commit 482604e2c9d66be67810b3906d3c501c4d46528e
Author: Carlos A. Munoz <camunoz@redhat.com>
Date:   Mon Dec 1 11:11:04 2014 +1000

    Remove the need for a custom standalone.xml when installing Zanata.

commit 362a2653d51ba402a84e56a22835b0677c558174
Author: Carlos Munoz <chavo16@hotmail.com>
Date:   Fri Nov 28 15:38:48 2014 +1000

    Add missing newline characters and change shell scripts.

commit a99f9310d418bb560ae6ecadb9c31789d5ab86f1
Author: Carlos A. Munoz <camunoz@redhat.com>
Date:   Fri Nov 21 12:07:58 2014 +1000

    Add zanata-overlay submodule.

    This submodule takes care of building an overlay zip file that when extracted on top of the different supported JBoss distributions, will supply the necessary components for Zanata to run. In this iteration it contains:
    - Necessary jboss submodules
    - Configuration and startup scripts for zanata
    - Installation scripts which fetches the war file from the web and configures some parts of the application.

    Currently, it builds 2 distributions:
    Wildfly 8.1
    EAP 6 (6.3 recommended)