v0.7.0

Introduces some more significant changes, hence the minor version bump in
such a short time frame.

* Rename pg_database_size to pg_database_size_bytes in queries.yml.
* Add pg_stat_statements to sample queries.yml file.
* Add support for optional namespace caching. (#319)
* Fix some autodiscovery problems (#314) (resolves #308)
* Yaml parsing refactor (#299)
* Don't stop generating fingerprint while encountering value with "=" sign (#318)
  (may resolve problems with passwords and special characters).