support for indigo and fix for precise and saucy

indigo: 
reimplementation of the pbuilder_calls script in python. 
process-call behaviour changed by using non-blocking calls to avoid suspended
skript caused by zombie-child-processes. for this the command-dispatcher 
is used. 

precise:
for the python-wstool-package manual intervention due to broken 
package-dependecy is necessary

saucy:
seems that required package curl-ssh only available for lts versions