Merge pull request #34 from latestrevision/fix_date_serialization

Serialize incoming zoned date/datetime instances into strings of the app...
Merge branch 'fix_annotation_handling' into develop

Conflicts:
	taskw/test/test_utils.py
	taskw/utils.py
	taskw/warrior.py
Avoid hardcoding TZ in the test expectation.
Add functionality for marking existing task as started/stopped.
Return stdout or stderr from task_info.
Merge pull request #36 from latestrevision/add_start_and_stop

Add functionality for marking existing task as started/stopped.
Merge pull request #37 from latestrevision/fix_info_method

Return stdout or stderr from `task_info`.
Removing duplicated encoding of string types.
Merge pull request #38 from latestrevision/remove_duplicated_encoding_for_string_items

Removing duplicated encoding of string types.
Convert 'None' into an empty string; otherwise, we will ask task to set various fields to the string value None.
Merge branch 'properly_empty_values_upon_null' into inthe_am

Conflicts:
	taskw/utils.py
	taskw/warrior.py