fcm make: log file improvements

Print FCM version string to log.
In incremental mode, log files from previous run are retained.
New `fcm version` command to print FCM version string.
Remove dependency on HTTP::Date
Merge branch 'master' into log
fcm version: improve display
FCM::System::Misc: fix comment
FCM::Util: fix extra space
Merge pull request #63 from matthewrmshin/log

fcm make: log file improvements