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
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.
Fix global ``` self.root = false ```

Using the on_load hook does not change the defined root on
Serializer#inherited.

Related to #179
Add failing test to show behavior of custom serializer with nils.
Gemfile improvement in README
Merge pull request #206 from kirs/patch-1

Gemfile improvement in README [ci skip]
Create DefaultSerializer so that as_json uses same interface.

This is to ensure that PORO's as_json is called if no serializer
is specified.

Original behaviour was that serializable_hash was being called,
overriding the as_json method.
Move DefaultSerializer from array_serializer.rb to serializer.rb
Remove pry-nav from gemspec.
Restore order of fields in hash to original order.
reduce 2x map; fixes datamapper eager loading
Merge pull request #210 from tpitale/master

Reduce double map to once; Fixes datamapper eager loading.
test cases by fblee

Merge remote-tracking branch 'fblee/master'
serialization test: respect root settings when root object is nil
Don't fail if object is nil, render null
Add ActiveSupport::DescendantsTracker to Serializer and ArraySerializer
Remove caching of Serializer constants to allow ActiveSupport::Dependency reloading to work