migrate cc.redpen.docvalidator.* to cc.redpen.*

docvalidator is the old code name for redpen.
redpen.docvalidator.* sounds redundant.
rename groupId
DocumentValidatorRunner needs to be located at default package
DocumentValidatorRunner needs to be located at default package
Merge pull request #224 from recruit-tech/remove-docvalidator

migrate cc.redpen.docvalidator.* to cc.redpen.*
Add a get method to acess registered character by the value
Merge branch 'master' into get-method-with-character-value
Merge pull request #228 from takahi-i/get-method-with-character-value

Add a get method to acess registered character by the value