Created multipart module and moved multipart.py to multipart/encoder.py
Added MultipartDecoder.
Removed extraneous lines of code that were commented out.
Docstring improvements.

Added docstring for BodyPart.text and an example for MultipartDecoder where the MultipartDecoder was created directly (rather using the ``from_response`` helper).
Converted class methods that don't use cls parameter to static methods.
Changed to using email.parser-based parsing for headers.
Moved logic for dealing with no CRLF at the start of initial boundary from BodyPart to MultipartDecoder.
Removed equality operation from BodyPart; replaced in tests with checks against content.
Added myself to AUTHORS.rst under Patches and Suggestions.
Changes to Exceptions

*   Changed from explicitly declaring __init__ for exceptions but then only using the super().__init__ to just passing.
*   Moved the second Exception declaration so that they would be proximate.
*   Added both Exceptions to the namespaces of requests_toolbelt and requests_toolbelt.multipart
*   Added a test for BodyParts to ensure instances that are attempted to be created with content not containing CRLF/CRLF throw exceptions.
Converted BodyPart.text doctoring from having many lines to being a one-liner.
Factored out part of boundary construction.
Refactored parsing of body parts.
Refactored header parsing for BodyPart.
Refactored MultipartDecoder tests.

* Simplified version check code.
* Refactored tests with asserts using `all` to use iterators and for general clarity.
Merge pull request #15 from mythguided/multipart-response-redux

Adding Multipart Decoder, redux