move test builds into build/test
restructure rules directory

- move rule.ts and abstractRule.ts into language/rule
  in order to make rules pluggable
reworking build system
compile rules separate from core
rename rules for consistency

- also build and load all rules
create ruleLoader
compile core rules into build/
fix tests for pluggable rules
fix all tests
rename rules
fix module path
bump up npm version
pluggable formatters
fix formatters tests
update README for formatters
added support for external formatter module