年：
- Y: A full numeric representation of a year, 4 digits. Examples: 1999 or 2003
- y: A two digit representation of a year
月：
- m: Numeric representation of a month, with leading zeros. Examples: 01 to 12
- n: Numeric representation of a month, without leading zeros
- M: A short textual representation of a month. Examples: Jan to Dec
日：
- d: Day of the month, 2 digits with leading zeros. Examples: 01 to 31
- j: Day of the month without leading zeros.
示例：
Ext.Date.parse('2016/06/30', 'Y/m/d')
Thu Jun 30 2016 00:00:00 GMT+0800 (China Standard Time)
Ext.Date.parse('2016/6/30', 'Y/n/d')
Thu Jun 30 2016 00:00:00 GMT+0800 (China Standard Time)
Ext.Date.parse('2016/JUN/30', 'Y/M/d')
Thu Jun 30 2016 00:00:00 GMT+0800 (China Standard Time)
Ext.Date.parse('2016/6/1', 'Y/n/d')
undefined
Ext.Date.parse('2016/6/1', 'Y/n/j')
Wed Jun 01 2016 00:00:00 GMT+0800 (China Standard Time)
