Bump to version 1.3.0

Version 1.3.0 adds the following bugfixes and features:

* Remove python-xlib dependency by getting the socket path from i3
binary.
* The `Con::command_children()` method should work properly.
* Make `socket.recv()` robust against interruptions.
* Change `Con::mark` to `Con::marks` for the new ipc api (might be
breaking).
* Add `Con::window_rect` and `Con::deco_rect` properties.
* Fix encoding problems in reading README.
* `Con::workspace()` returns self if it is a workspace instead of None.
* Fix the ipc-shutdown event.
* The library is now installed as a directory instead of a single file.
* Make the main loop work in multi-threaded environments.
* Add Travis CI.
* Add a test suite.
* Add robustness against UTF-8 errors by replacing bad UTF-8.

Bump to version 1.2.0

Version 1.2.0 adds the following features:

* Obey I3SOCK environment variable
* Add Con::find_fullscreen()
* Added properties: `scratchpad_state`, `window_role`
* Con::find_marked() - make pattern optional

And the following bugfixes:

* Fix crash on `barconfig_update` event
* Use underscores to subscribe to `barconfig_update` event
* Correctly put floating nodes in the `floating_nodes` list of the Con

Bump to version 1.1.6

Version 1.1.6 adds the following bug fixes

* Use enum-compat instead of enum34
* Safely set window class and instance (fixes crashes for windows with
no class or instance)

Bump to version 1.1.4

Fixes the xlib dependency.

Bump to version 1.1.1

This version includes the following improvements:

* Python 2 support
* Support the `window_instance` container property
* Pep8 compliance code cleanup

Bump version to 0.1.1

Initial commit