Log Message:
Update ruby-pg to 0.19.0.

== v0.19.0 [2016-09-21] Michael Granger <ged@FaerieMUD.org>

- Deprecate Ruby 1.9

Enhancements:
- Respect and convert character encoding of all strings sent
  to the server. #231
- Add PostgreSQL-9.5 functions PQsslInUse(), PQsslAttribute()
  and PQsslAttributeNames().
- Various documentation fixes and improvements.
- Add mechanism to build without pg_config:
    gem install pg -- --with-pg-config=ignore
- Update Windows binary gems to Ruby-2.3, PostgreSQL 9.5.4 and
  OpenSSL 1.0.2f.
- Add JSON coders and add them to BasicTypeMapForResults and
  BasicTypeMapBasedOnResult
- Allow build from git per bundler.

Bugfixes:
- Release GVL while calling PQsetClientEncoding(). #245
- Add __EXTENSIONS__ to Solaris/SmartOS for Ruby >= 2.3.x. #236
- Fix wrong exception when running SQL while in Connection#copy_data
  block for output