Update build.xml file

[henning-gerhardt]

Updating build.xml file:

• fix different / mixed indent
• remove empty lines
• remove out commented or useless statements
• use properties instead of hard coded values

[henning-gerhardt]

@claussni @matthias-ronge : any comments for this changes?

[claussni]

Ant warning: "ugh/build.xml:58: warning: 'includeantruntime' was not set, defaulting to build.sysclasspath=last; set to false for repeatable builds"

Please set includeantruntime to false explicitly, as explained here: http://stackoverflow.com/questions/5103384/ant-warning-includeantruntime-was-not-set