Update retext to 0.2.0, retext-ast, retext-range
Refactor spec

This includes updates for retext@0.2.0
Remove testling
Update copyright in Readme.md
Update .gitignore, .npmignore
Fix property order in component.json, package.json, bower.json
Update Installation in docs

- Add Bower as an installation method;
- Rename Component.js > Component;
- Fix casing of NPM > npm.
Refactor API

Includes better error messages.
Remove browser test
Refactor Readme.md
Update changelog for 0.2.2
0.2.2