Bump the minimum Rails version requirement to 4.0.
Drop the Rails version-specific test hacks.
Fix PostgreSQLColumn constructor signature.
tsvector types are now supported out of the box in Rails 4.
Add a test for the geography type.
Fix up our additional type detection for geometry and geography.

This will allow us to avoid overriding other extensions that may already
provide this capability.
Detect for PostgreSQL's special `name` and `"char"` data types.
Extend the native database types Hash more directly.
Use @columns_hash instead of #columns.

The #columns method now returns copies of columns instead of a
reference.
Move the LIKE options creation to its own class.
Fix primary key detection.
Move the CHECK constraint collection logic into its own class.
Move the table SQL generation into a PostgreSQLSchemaCreation class.
Move OSX-specific gems to Gemfile.local.
Avoid double tagging test logging.