Logname and timestamp format

[HendriceH]

Hi @greole,
could you change the naming of all automatically generated logs/errorlogs to start with "log._. If you currently get errorlogs from a shell scripts, the log name starts with the script name and it is easy to accidentally delete the script when you want to clean the logs. Also it would be nice to have the timestamp without the ":" between the hours, minutes and seconds for handling in Linux.

[greole]

For newer version of obr we could read the log format string from .obr/config.