Added load_options/dump_options to MultiJson and adapters
Cleaned Oj and JsonCommon adapter using new Adapter.defaults API
Removed unused code from specs
MultiJson does not modify arguments

Related to #92
Outdated documentation
Add Coveralls for code coverage reporting
Cleaned up some specs
Cleaned specs a bit more
json_gem and json_pure should be available on all platforms

This should increase coverage a bit.
Global options have priority over adapter options
Clean specs
Enabling quirks_mode by default for json_gem/json_pure adapters
JSON common adapter does not modify input string encoding
Add JrJackson adapter
Extracted common code from okjson and jrjackson adapters
Raising ArgumentError on bad adapter input
Prepare for 1.7.0 release
Add JrJackson to readme
Remove gratuitous nodoc comments [ci skip]
Convert aliases to use bare words instead of symbols