Add helper to SCR base class to have DRY way to get path on target root
adapt resolver agent to respect target root
adapt modules agent to respect target root
adapt any agent (part which touches file) to respect target root
Adapt ini agent to respect different root

Due to split of IniAgent to more component it is not so straight
forward, but there should be enough comments explaining why everything is
neeeded.
changes
Merge pull request #48 from yast/adapt_agents2

Adapt agents2