webos-filesystem-paths: Add new variables for various locations

:Release Notes:
Add these variables:
  webos_downloadeddir (better name for webos_appstoragedir)
  webos_downloaded_applicationsdir (better name for webos_installedappsdir)
  webos_downloaded_frameworksdir
  webos_downloaded_pluginsdir
  webos_downloaded_servicesdir
  webos_firmwaredir
  webos_mountablestoragedir (better name for webos_localstoragedir)
  webos_persistentstoragedir
  webos_pluginsdir
  webos_udevscriptsdir

:Detailed Notes:
Add commentary on the semantics of various locations.

:Testing Performed:
The output from
  $ make BBFLAGS=-e cjson | grep 'export webos_' | sort
shows that the variables have been set correctly.

:QA Notes:

:Build Notes:
This commit invalidates all shared state.

:Issues Addressed:
[GF-5208] Add /usr/palm/plugins location to webos-filesystem-paths.inc
          and webOS.cmake
[GF-9235] Add /media/cryptofs/data location to
          webos-filesystem-paths.inc and webOS.cmake
[GF-9470] Add /lib/firmware location to webos-filesystem-paths.inc and
          webOS.cmake
[GF-9472] Add /lib/udev location to webos-filesystem-paths.inc and
          webOS.cmake
[GF-9473] Add filesystem path variables for downloaded component
          locations

Open-webOS-DCO-1.0-Signed-off-by: Herb Kuta <herb.kuta@lge.com>
Change-Id: I7abdd55ecd43268111778c00f3c021fa169667c8
Reviewed-on: https://g2g.palm.com/2849
Tested-by: Herb Kuta <herb.kuta@lge.com>
Reviewed-by: Build Verification
Reviewed-by: Susan Montooth <susan.montooth@lge.com>