use json whitespace

Use JSON whitespace: <SP>, <TAB>, <CR>, and <LF>.
Throw on any characters with a Unicode code point value of 0x1F or less.
add test case for duplicate keys
allow duplicate keys in objects
fix travis-ci node versions
fix indent size
convert source to string

http://es5.github.io/#x15.12.2
break single line comments on \r
use es5 whitespace

Use ES5 whitespace, minus Unicode
Merge pull request #60 from jordanbtucker/use-json-whitespace

Use ES5 whitespace