When MySQL sql_mode is set to strict (STRICT_TRANS_TABLES or
STRICT_ALL_TABLES), the DB rejects the date insertions in ISO-8601
format (yyyy-mm-ddThh:ii-ssZ) as sent by GitHub with error "Incorrect
datetime value".

This commit converts the date to ISO-9075 format as accepted per MySQL
documentation [1]

[1] http://dev.mysql.com/doc/en/date-and-time-functions.html#function_get-format

Fixes #39