Upgrade to Grails 2.3.5. Upgrade spring-security

Attention: configuration for Spring Security changes from
grails.plugins.springsecurity to grails.plugin.springsecurity.
[CHERKASY-51] Add plugins: oauth provider and rest-api
Merge pull request #43 from thehyve/features/CHERKASY-51-oauth2

Features/cherkasy 51 oauth2