Logstash 1.2 format support

Rewrite of the logstash tt files. New structure supports 
- conditional plugins (to replace type), limited to 1 level for now
- ordered plugins
- a generic way to extend plugins

Most deprecated features of 1.2 are not supported, except for the exclude_tags in the mutate filter. To replace this one, a second level conditionals is needed.

Use the main.tt to generate the complete configfile.