improve documentation
improve documentation

This includes fixes for displaying code inside of the README
and actually adds information on certain topics.

---------------------------------

Squashed commit of the following:

commit 50f80d5d237059212bec9c4b30da3a23f090b398
Author: Tim Reddehase <tredd@informatik.uni-bremen.de>
Date:   Tue Jan 6 15:26:35 2015 +0100

    fix README documentation for rake task.

commit ed99726a664bbe8404860dd7d14dd5e17ce4fb11
Author: Tim Reddehase <tredd@informatik.uni-bremen.de>
Date:   Tue Jan 6 14:54:09 2015 +0100

    fix code indentation in markdown README.

commit eda5ea6a9da23a25ebdd92fb7979d30c802b43e0
Author: Tim Reddehase <tredd@informatik.uni-bremen.de>
Date:   Tue Jan 6 14:48:15 2015 +0100

    add XML retrieval alternative to README.

commit bc6778fab0d19809dd4aeedbc86886ac5d358e1e
Author: Tim Reddehase <tredd@informatik.uni-bremen.de>
Date:   Tue Jan 6 14:47:39 2015 +0100

    add portion on constraints to README.

commit a7622a03d0c4e7598be17f1bfb122799a1ecf780
Author: Tim Reddehase <tredd@informatik.uni-bremen.de>
Date:   Sat Dec 13 18:12:05 2014 +0100

    improve explanation of config/routes.rb changes.

commit 1f7fcf100939a18d2ea161f5bcaa875dc3d46e67
Author: Tim Reddehase <tredd@informatik.uni-bremen.de>
Date:   Sat Dec 13 18:11:22 2014 +0100

    change styling of code examples in README.

0robustus1/specroutes,0robustus1/specroutes,0robustus1/specroutes