Logrotate Docker Image 1.2

Added features:

• #20 Options for delaycompress and rotation handling: https://github.com/blacklabelops/logrotate#turn-off-log-file-delaycompress
• #14 How to send a signal post/pre rotate. Description can be found here: https://github.com/blacklabelops/logrotate#custom-skript-execution
• #17 Add support for maxage and minsize

Improvements:

• #18 LOGROTATE_INTERVAL now automatically adjusts cronschedule. Setting both cron and interval is not required anymore.
• #21 Don't crash if given directory doesn't exist