Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/3fe4d06741f2
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #18937 from AshayNeema/Bug_993887_System_Banner_wont_disapper_issue

Bug_993887 System Banner wont disapper issue

========

https://hg.mozilla.org/integration/gaia-central/rev/118815c76a7a
Author: ashay.neema <ashay.neema@lge.com>
Desc: Bug_993887 System Banner wont disapper issue

Bug_993887 Fix TestCase

========

https://hg.mozilla.org/integration/gaia-central/rev/2ee9ddc6112b
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #19384 from lhadji/1007568/copy-symlink

Bug 1007568 - Follow symlinks when copying apps into STAGE_DIR, r=yurenj...

========

https://hg.mozilla.org/integration/gaia-central/rev/aa56a9402963
Author: Leila Hadji <leila.hadji@sonymobile.com>
Desc: Bug 1007568 - Follow symlinks when copying apps into STAGE_DIR, r=yurenju

Directories under GAIA_APPDIRS might contain symlinks
(e.g. outoftree_apps). When copying the symlinked apps
into STAGE_DIR without -L option, clear-stage-app
will remove the files in the target directory.
Bumping manifests a=b2g-bump