[enhancement] bumped dependency versions
Merge pull request #34 from dacrome/bumped-dependency-versions

[enhancement] bumped dependency versions
define explicit the header name in annotation
define explicit the parameter name in annotation
Merge pull request #35 from sschum/spring_identifier

define explicit the heder/parameter name in annotation
Added plugin mechanism for pre registration checks. Refactored the project to have a parent pom which builds the plugin, its example implmentation and the self registration module in the correct order.
restructure project structure of self-administration
optimize pom-files
rename plugin packages
refactor pluginhandler mechanism
use user instead of email as string
if an plugin-error occures:
 * the error message will be shown
 * the user will not be register
check the email from user
check ".org" suffix instead of ".com" (needed by Integrationtests)
added plug-in method for post registration actions
perform post registration actions
- /s/Plugin/CallbackPlugin/
- moved exceptions to separate package
- JavaDoc
use only one exception
extends example-plugin by add-group-mechanism
make constants configurable (needed by integrationtests)