Merge branch 'release/0.5.0' into develop
Add workaround for TW-1452 bug
Task: Perform done and deleted operations only when necessary
Use uuid fields intead of ids where possible

IDs can get non-unique with completed tasks, which makes modifications
or deletions of particular completed tasks impossible.
Task: Load task uuid when saving a new task

A new task can not refresh its data since it has not set uuid/id.
We need to parse the output of the 'task add' command.
Task: List all non-readable fields as modified when creating new task
Task: Add NotSaved exception
Task: Allow setting attributes via keyword arguments
tests: Do not use TW directly to create tasks
tests: Add tests to filter by attributes and their empty values
Task: Raise exceptions via Task class reference
tests: Add basic Task tests
TaskWarrior: Detect task version
Task: Add workaround for task bug in older versions, which eats up a part of description
tests: Make tests Python 2.6 compatible, avoid using assertRaises as context manager
Merge pull request #11 from tbabej/improve_task_object

Number of improvements
Merge pull request #9 from tbabej/fix_tw1452

Add workaround for TW-1452 bug
Don't explicitly require six==1.5.2 to avoid VersionConflict error
The next version will be 0.6.0
Add AUTHORS file