NXP-10566: more comment on el deps, and add back juel-impl dep declaration
NXP-10566: align el-api on tomcat 7 provided lib
NXP-10566: use a patched version of juel-impl to prevent it from being chosen as the default expression factory instead of the one from jboss-el
NXP-10566: temporarily remove the provided scope from tomcat-el-api, waiting for it to be referenced explicitely in all submodules
NXP-10566: put back provided scope for tomcat-el-api