first approach to logrotate
added test, review fixes
logrotate test: check that logs are not empty
reopen ubic_log on sighup
rename 'reload_signal' option in Ubic::Daemon to 'proxy_logs'

it's really a boolean flag with semantics different from
Ubic::Service::SimpleDaemon's 'reload_signal' option.

Also, some new perldocs.
logrotate test: test for "reopened" message
Merge branch 'logrotate'

https://github.com/berekuk/Ubic/pull/47
preparing for 1.48_01 release
v1.48_01

    * guardian supports logs proxying and reopening them on SIGHUP
     (see https://github.com/berekuk/Ubic/pull/47)
    * hint about 'ubic help' on unknown command