Adding date-based sorting for Push Message information table

Conflicts:
	model/api/src/main/java/org/jboss/aerogear/unifiedpush/dao/PushMessageInformationDao.java
	model/jpa/src/main/java/org/jboss/aerogear/unifiedpush/jpa/dao/impl/JPAPushMessageInformationDao.java
	model/jpa/src/test/java/org/jboss/aerogear/unifiedpush/jpa/PushMessageInformationDaoTest.java
Merge branch 'date_sorting'
instead of validating an entity from the database, we validate the new from the update form