fixing indentation which has too much spaces
Ensuring that cached state is never too old

Reusing old cached state leads to a lot of problems (bad dependency
resolving if things have changed, problems with backwards compatibility
when service classes change, ...).
The `restore_current_state` function now provides the guarantee that the
restored state will never be older than x seconds (x=10minutes
currently).

This behaviour can be toggled with the `must_be_fresh` kwarg.
The `info` command requires this, for example - we may render the
cached state even if it is too old, it's just a visual thing and does no
mutation.
reuse `get_age...` instead of recomputing it
AFAIK we don't need any of this
explaining why we need to rm -rf in .travis.yml
fixing typo
unifying cache age in info with expiration

Red cache in info means it's too old and will need to be re-fetched when
running a command such as status.
Merge pull request #13 from yadt/feature/fresh_status

Feature/fresh status