modified build.xml to allow mysql root user without password

Hello,

since we want to test what we develop we should provide the developer with the required environment.
This adds the composer.phar and the dev-dependencies like phing, phpunit, etc.

Also the changes in build.xml allow to use `-Dmysqlrootpass=''` if the root user has no password. 

I would have preferred not to set the dependencies under version control, but you actually have to own a github accout to successful install all dependencies, so its no option to leave this job to jenkins.

This is more of a suggestion than a must have, although it would help to integrate unittests in our workflow. All comments are appreciated.

Greetings from Leipzig University Library,
Ulf Seltmann