more documentation for auto-annotate and rake tasks

the docs for auto-annotating were kind of buried inside the Rails Config section, so I extended them and added a reference to them inside the Usage section

Update README.rdoc

Remove new line before annotation wrapper closing statement

Set model_dir to ["app/models"] if not set (fixes #265)

Runs annotate on 'rake db:rollback' too

show foreign keys when run on rake task

ignore default value for jsonb

Quote each value in default arrays

Previously, quoting an array fell back to `inspect`, which is ok for
strings, but not good for BigDecimals, for instance.

Annotate fixtures for nested models

Invoke get options task before annotating migrations

[ fixes #252 ]

This reverts commit 067ce522.

Prefer SQL column type over normalized AR type

fix issue where serializer-related flags weren't being honored

Check if model has skip tag in annotate_model_file

Potentially addresses issue# #167
Annotate_model_file is called automatically on all files in models directory and does not check if model contains SkipSchemaAnnotations tag.

Adds support for foreign key annotations

Test on Ruby 2 versions

Do not add excessive blank lines when source has Windows EOLs