e-wm: use ESYSACTIONS,EMENU,ECONFIG,ETHEME variables instead of hardcoded e-wm-sysact...

e-wm: use ESYSACTIONS,EMENU,ECONFIG,ETHEME variables instead of hardcoded e-wm-sysactions/e-wm-menu runtime dependency

* ILLUME_THEME/ILLUME_CONFIG were renamed to ETHEME/ECONFIG to use the
  same variable names as task-demo-x11/task-beagleboard-*

* e-wm-sysactions-shr doesn't need RPROVIDES anymore

* fixes last multiple providers notice I had
  NOTE: multiple providers are available for runtime e-wm-sysactions (e-wm, e-wm-sysactions-shr)
  NOTE: consider defining a PREFERRED_PROVIDER entry to match e-wm-sysactions

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>