Use proccess.env as state storage for environ (see bem-project-stub#process-env)
Use ENV_ROOT as lib root storage
Block-elem naming scheme reverted to original b/__e
bem-html lib removed from dependencies; bem-pr added
package.json fixed
Nodes refactoring
Site root prototype level updated
Site#createOutputNode refactoring
Nodes refactoring
SetsNode added
bem-pr added
Gitignore fixed