Implementation of TTL and one index per tenant

Log records are now written to a separate index per tenant
A separate doc type is created for EventProducer patterns
Indexes are created upon tenant creation with a default doc_type
TTL mappings are made when an index is created or a new doc_type is mapped for EventPRoducer Patterns
Default TTL values are configurable in the meniscus.conf file.
Default TTL values are applied to all messages inserted into ElasticSearch

Addressing:
Issue #437
Issue #416