Implemented 'code_changes' metric with the following optional parameters:

• period:
  • Specifies the periodicity.
  • Can be set to 'day', 'week', 'month' or 'year'.
  • Defaults to 'day'
• begin_date:
  • Specifies the beginning date.
  • Possible values: '2018', '2018-05', '2019-05-01', ..., ' 2017-03-02 05:34:19'
  • Defaults to '1970-1-1 0:0:0'
• end_date:
  • Specifies the ending date.
  • Possible values: '2018', '2018-05', '2019-05-01', ..., ' 2017-03-02 05:34:19'
  • Defaults to the current date and time

Example Output:
ag.code_changes('augur', period='year')

ag.code_changes('augur', period='month', begin_date='2018', end_date='2018-06')

Signed-off-by: Parth Sharma parth261297@gmail.com