Add general purpose filter query parameters to REST API

[peterschwarz]

On routes that return lists of resources, if there is a query parameter that doesn't match any other parameters, the REST API should assume it is a filter, and only return resources that match that filter.

For example:

/batches?batcher_pubkey=02d260a46457a064733153e09840c322bee1dff34445d7d49e19e60abd18fd0758

Should only return batches with a batcher_pubkey that matches "02d260a46457a064733153e09840c322bee1dff34445d7d49e19e60abd18fd0758".

Features:

• Comma separated values behave as a logical
• Dot nation can be used to reference nested keys or indexes
• header. can be omitted from the beginning of header keys

(Duplicated by https://jira.hyperledger.org/projects/STL/issues/STL-224)