Fixed ERRAI-765 -- The ListWidget now destroys widgets after removing them.
ListWidget also throws an InvalidBeanScopeException if its contents are not dependent scoped.
minor cleanup: removed unneeded imports in ListWidget
Create errai-security-keycloak module for errai-security integration with Keycloak.

The module contains an AuthenticationService implementation and filters for processing
an errai-security user from a Keycloak AccessToken.
Add documentation for setting up errai-security-keycloak and using it with the errai-security-demo.
Added widget destroy functionality to ListWidget.onItemsCleared()
Update picketlink version to 2.6.0.Final.
Move and rename UserExtractionFilter -> UserCookieFilter and move to errai-security-server.

This filter is no-longer keycloak-specific. The .properties handling code has also been factored out into a producer mothod.
Move mock servlet classes to errai-security-server so they can be shared by other errai-security-* tests.
Only create one instance of Wrapped AuthenticationService in KeycloakAuthenticationService.
Avoid invalid cast when generating foreach loops
Create unit tests for errai-security-keycloak and UserCookieFilter.
Add missing license headers to java source files in errai-security.
Remove user cookie encoding from FormAuthenticationScheme (UserCookieFilter should be used instead).
Add patched JUnitShell to workaround GWT issue: https://code.google.com/p/google-web-toolkit/issues/detail?id=8422
Update version of Errai used for forge addon tests.
Fix classpath order in errai-jpa-datasync/errai-ui so that errai-common JUnitShell is loaded before gwt-user.
Upgrade old cdi-api version in errai-version-master.
Comment out keycloak auth method so that demo runs outside of Keycloak server by default.
Resolve ERRAI-766: add destroy method to client-side Instance implementation.
ERRAI-740: Linker for permutation specific cache manifest files