added mailconfig, assemble configuration.yml from dir

* mailconfig.yml is created if mailconfig.yml.j2 exists in the playbook
* config/configuration.yml.d is assembled to  configuration.yml
removed misleading README parts, removed useless sudo
configuration.yml revised

* splitting / merging yml files is hard without yaml tools...
* split yml files in config files for each environment
* only config_env_production.yml possible now, so somewhat limited
  * we don't support multiple DB envs either, so no problem atm :)
use supervisor for nginx, reinstall nginx on passenger version change

* removed debian nginx init script
* always reinstall nginx if passenger version changed to update
  integrated passenger module
new var server_name

* replaces ansible_fqdn as nginx and redmine_git_hosting server name
* default value is ansible_fqdn
SSL security: params to separate file, generate dhparam

* dhparam with 2048bit is generated if not present
* removed RC4 ciphers
* removed SSLv3
redmine_dmsf removed all workarounds

* problems fixed upstream, so no workarounds needed anymore
added OCSP stapling, generate self-signed cert on demand

* generate cert if the given cert name doesn't exist and ssl_create_self_signed_cert is set
* added params for OCSP stapling
* defaults file cleaned up a bit
* some var renames