Python-jsonschema-objects

Bugfixes:
+ Removes an extraneous __str__ method from classbuilder (h/t edwardcwang)
+ Ensures 'strict' is passed for definitions as well as main schema classes (h/t neyguvj)

**Bugfixes**

+ Fixes an issue where top level array item constraints weren't actually converted to class wrappers.

**Other Things**

+ Added a section to the README explaining how to create multiple top-level objects.

**Bugfixes**

+ Fixes an issue with opening schema files on systems without a default UTF encoding (65)
+ Updates equality comparisons to check class type before making assumptions about what methods exist (72)
+ Moves requirements into setup.py to better support library use. Also loosens specification of jsonschema as a requirement to allow more versions. (69)

**Bugfixes**
- Fixes a bug where calling build_classes twice could cause a fatal error due to re-use of the schema object

Bugfixes:
- Parameters that start with underscores no longer get lost if schemas are updated (h/t schuyler-glympse)
- Adjusted the type checking resolution order to make sure booleans don't accidentally get accepted because of Python truthiness (h/t blr246)
- Use JSONSchema to validate input schemas before attempting to build objects from them, to avoid the creation of inscrutable errors
- Fix a number of issues with array validation and serialization (esp. with nested arrays)