Add support for meta key

Test for meta_key serialization
Remove unneeded method aliasing of attribute reader: object, with the underscored class name of serializer, to fix issue where a model's attribute name matches that of the underscored prefix of the serializer
Merge pull request #138 from tchak/meta

Meta object
Adding optional type for attributes
Adding info to the readme on how to specify the type, adding an additional
test to cover a computed property without a type
Added description of default_serializer_options 

In example it's used to set up root: false for controller
Take a stab at documenting AMS support.

Specifically when used in objects that are not ActiveRecord objects.
Test : use a deducted serializer on non-ActiveRecord models
use id methods
remove debugging code
Merge pull request #173 from jacortinas/document_ams_support_include

Document adding serializer support to normal Ruby classes and other ORM's.
Merge pull request #176 from hmsimple/id-methods

Use pluck(:id) or _id methods instead of associated objects
Merge pull request #175 from jlecour/deducted_serializer_test

Test : use a deducted serializer on non-ActiveRecord models
Append an `_id` or `_ids` suffix to associations' keys. Embed objects in root according to their serializers' names.

An `_id` suffix will be appended to the name of HasOne associations, while `_ids` will be appended to the singularized name of HasMany associations. Association keys can still be overridden with the `key` option.

Furthermore, objects embedded in the root are now by default named according to their serializer, instead of the key used for their associations.
use _ids method instead of pluck
Merge pull request #177 from hmsimple/fix-id-methods

use _ids method instead of pluck to embed ids
Merge pull request #169 from dgeb/embed-with-id-suffix

Update foreign key naming conventions - fixes #158
Merge pull request #161 from kevins90/fix_attr_name_as_serializer_underscored_prefix

Fix serialization of attribute whose name matches the serializer prefix underscored
Add support for specifying the serializer for an association as a String.

This enables the deferral of the resolution of the serializer class to prevent NameError exceptions due to reference cycles between serializer classes.
Update README.md

Spelling and murkup mistakes fixed.