Merge pull request #2 from haozi89/master

add enable request cookie to builder
rename parseJson to performParse;
rename methods;
Update README.md
1.rename method name;
add desc for image downloader
1.working on disk cache invalidate and fetching the disk data;
Merge branch 'master' of
https://github.com/androidzhaoxiaogang/rocket.git
add cookie support;
removed the unused CookieManager file;
add api cache strategy-----use JsonBuilder & request to build and pass strategy