add function(add) to main.js
Merge pull request #24 from kyatabe/add

add function(add) to main.js
`add`, `sub`, `times`, `divide`, and `change`
change 'inputValue' function to 'calculatorHundler' function
add InputFilter function
add 'Calculator.Hundler'. Now it's working.
Merge pull request #29 from kishizuka/main_logic

Main logic