Add .gitignore file

.gitignore file is added in the project
Add grailsApplication in OauthCallBackController

grailsApplication is used to get variable value from config file.
Add spring security core plugin
Add role and user from BootStrap
Create User, Role and UserRole and import them in Bootstrap
Use reauthenticate using email
Change getByUsername to findByUsername

Capitalize is_authenticated_anonymously
Add plugin controller in permitAll
Remove files from target and target-eclipse folder to make .gitignore effective