Makes attribute_map optional for serializing

[milancermak]

Description

Instead of having duplicated keys between attribute_map and deserialized_types, this PR allows to completely leave out attribute_map in serialized classes, if you don't want to do any renaming between the native and serialized representations.

An example:

class User:
    deserialized_types = {
        'name': 'str',
        'age': 'int'
    }

    def __init__(self, name='', age=0):
        self.name = name
        self.age = age

u = User('joe', 42)
serializer = DefaultSerializer()
serializer.serialize(u) # {'name': 'joe', 'age': 42}

Motivation and Context

This PR is a follow-up on the discussion in #58. I'm using the serializer in my projects too, as I found it super useful. However I found the repetition of attribute names unnecessary and decreasing the readability of my models.

Testing

I ran the tests locally (OS X, py3.6), all passed. Note I didn't add new tests to cover this functionality as it is only in discussion/evaluation phase. I'm happy to add some if you find the change acceptable.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[nikhilym]

Thanks @milancermak . We will review the code and get back to you soon.

[nikhilym]

These changes seems to be good @milancermak . Can we add some test cases to these changes and also update the docstrings for the serialize and deserialize methods, to reflect the functionality change?

Once the PR gets pushed, we can update the attribute management doc section as well with a note that users can use the DefaultSerializer class for their serialization/deserialization provided they have the deserialized_types map

[milancermak]

Thanks @nikhilym. I did so in the last commit, can you have a look and tell me if there's anything missing? There was not that much docstrings to update.

[nikhilym]

Hey @milancermak. I have updated the docstrings and pushed in your changes to the repo. Thanks again for sending in the PR. I will update the PR once a new SDK is released with the changes on PyPI.

[nikhilym]

Release 1.6.0 contains the changes.