Since every event is tied to a category, it's better for event object to have it as a member method
Change-Id: I911415284486bb11d13d91366340c5c330317c34
patch set 3:
* add gender support to various messages
* tweak variables a little bit, e.g. move class variables to function local variables
patch set 4:
* update various email to e-mail in i18n file
* add support to process only valid echo events
* add global email footer
* add the new table schema to core schema file
patch set 5:
* remove trailing white space
* add missing semicolon to return statement in Notifier::notifyWithEmail()
patch set 8:
* some change based on newest feature requirement
Change-Id: I3298617dab4c04c4d6d486469120fc2d0c986b66
