Update travis test environment
Fix travis build
Update postgresql and openssl versions for windows cross build.
Fix cross build for mingw32.
Travis uses the Gemfile, so 'gem install' is obsolete.
Add Connection.conndefaults_hash and add specs for conndefault variants.
Merge branch 'master' into column_type_mapping

Conflicts:
	.travis.yml
'gem install rake-compiler' is still needed for cross build.