Add plugins page

.travis.yml

README.md

package.json

scripts/helpers.js

scripts/tags.js

source/_data/languages.yml

source/_data/plugins.yml

source/_data/themes.yml

source/plugins/index.md

source/zh-tw/api/index.md

themes/navy/layout/archive.swig

themes/navy/layout/index.swig

themes/navy/layout/partial/after_footer.swig

themes/navy/layout/partial/header.swig

themes/navy/layout/plugins.swig

themes/navy/layout/post.swig

themes/navy/source/css/_partial/common.styl

themes/navy/source/css/_partial/plugins.styl

themes/navy/source/css/navy.styl

themes/navy/source/js/plugins.js