added Makefile
manuall start cron
shutdown container gracefully
set the locale to C.UTF-8 using update-locale tool
dockerfile: cleanup
install: moved imagemagick hack before gem cache copy
specify `daemon off` option using `-g` cli flag
added REDMINE_HTTPS_HSTS_MAX_AGE configuration option
added REDMINE_HTTPS_HSTS_ENABLED configuration option
readme: add section on `Configuring HSTS`
Merge branch 'hsts-config'
readme: fix typo