Refs #17503 Reimplementation of Validate emails using threads in backed

In this way the server is able to serve future clients requsts with
minimum interference.

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/naaya.content.talkback@20538 a0171fae-0946-0410-966d-b1775066cd26
Email Validation - resolve validation in backend threads (avoid server load)

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/naaya.content.talkback@20539 a0171fae-0946-0410-966d-b1775066cd26
release 1.4.28, new version 1.4.29

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/naaya.content.talkback@20540 a0171fae-0946-0410-966d-b1775066cd26
release 1.4.28, new version 1.4.29

git-svn-id: https://svn.eionet.europa.eu/repositories/Naaya/trunk/eggs/naaya.content.talkback@20543 a0171fae-0946-0410-966d-b1775066cd26