bumped version to 0.16. 

bumped version to 0.16. 

feature: added an optional len parameter for resty.md5.update(). (#33) 

bumped version to 0.14. 

bumped version to 0.14. 

feature: added parameter check for aes.lua. 

add more doc and fix buffer length error. 

bumped version to 0.12. 

doc: updated the copyright years.