dont crash on unexistent multi-nested field access
fix multi-nested field creation
inputs: pipe: retry on failure

https://logstash.jira.com/browse/LOGSTASH-966
Merge pull request #619 from jdve/master

inputs: pipe: retry on failure
version dev
- update changelog for #619
Merge pull request #604 from gza/master

Some fixes for nested fields
Merge git://github.com/logstash/logstash