Restructure project

New project layout to prepare for future enhancements, and start adding
mapping to more API functions.

Added support for binary attribute values (thanks @ereOn !).
Support for ldap_add* and ldap_modify*

Add the Changeset class to describe a list of operations to apply in a
modification operation.
Package import for Python 3.x
Asynchronous API support

Add Future object, and expose asynchronous APIs.
Binary operations continued

Fix LDAPMod construction, and add a few unit tests for Changeset object.
Usual Python 3.x fixes
Bugfixes and test coverage
Unit tests
Unit tests
Bug fixing and code coverage

Reach 100% code coverage for Python 2.x and 3.x.
Update README and CHANGES
Push version to 0.3.0
Merge pull request #4 from icecrime/0.3.0

Version 0.3.0