User friendly JSON dumps

essentials includes an user-friendly json.JSONEncoder class, handling these common objects:

• datetime
• date
• time
• UUID
• bytes That cause a TypeError exception when using the default JSONEncoder class.

Example:

from datetime import datetime, date, time
from essentials import json

# a datetime is serialized in isoformat
data = json.dumps({'value': datetime(2016, 3, 26, 3, 0, 0)})
assert '{"value": "2016-03-26T03:00:00"}' == data

# a date is serialized in YYYY-MM-DD format
data = json.dumps({'value': date(2016, 3, 26)})
assert '{"value": "2016-03-26"}' == data

# a time is serialized in hh:mm:ss format
data = json.dumps({'value': time(10, 30, 15)})
assert '{"value": "10:30:15"}' == data

# bytes are first base64 URL safe encoded, then decoded into UTF8 strings
data = json.dumps({'value': b'Lorem ipsum dolor sit amet'})
assert '{"value": "TG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQ="}' == data