Merge changes from origin/7.1

8ce6565 Fixes normal drag and drop events (regression since 7.1) and html5 style D&D in IE10 (#12339)
5fb1da2 Publish error artifacts immediatly in TeamCity
649735f Added user agent for IE 11 (#12631)
a5795f3 Prefixes GET parameters in Liferay with portlet namespace #12602
b235d9c Refactor how TB3 tests are written (#12572)

Change-Id: Ia8281fb81d371dd4813371d62890a1ed34990d35

diff --cc client/src/com/vaadin/client/ApplicationConnection.java
Simple merge

diff --cc server/src/com/vaadin/server/VaadinPortlet.java
Simple merge

diff --cc shared/src/com/vaadin/shared/ApplicationConstants.java
Simple merge