LDEV-3275: Put /userfiles dir in each LAMS WAR.
The ApplicationContext class from Tomcat embedded in JBoss allowed getRealPath() to return proper path even for non-existent resources. Undertow's FileResourceManager returns null in such cases.
This prevents CKEditor Connector servlet from initialising as it checks the path where it later stores files.
Alternative solutions are:
- configure the servlet to use a dir present in all WARs, like "META-INF"; this in counter-intuitive and does not follow WAR structure guide
- upgrade to newer CKEditor connector servlet; makes sense as we use very old one, made for FCKEditor, and the new one is available; it requires some work, though
- patch the servlet's initialisation code so it creates the dir by itself; this would result in LAMS custom CKEditor connector library
