Bug 1041710: ensure that wallpaper size always exactly matches screen size

when computing screen size for wallpaper pick activity use Math.ceil to get 854 instead of 853.5 for FWVGA

Unit tests for wallpaper_manager.js plus fix a broken bootstrap test

address review comments
(cherry picked from commit 7815e901b5ccec40b22987a10d002bb1225d8d17)

Conflicts:

	apps/settings/js/panels/display/wallpaper.js

remove special low-tolerance case for PNG image comparison in image_utils unit test because it caused failures on TBPL
Bug 1044019 - Add /storage/sdcard to cleanup_storage in gaia test
Merge pull request #22253 from viorelaioia/bug_1044019_v2.0

Bug 1044019 - Add /storage/sdcard to cleanup_storage in gaia test
Bug 1030249 - Notify the server if Find My Device is disabled.
Merge pull request #22262 from mozmark/bug1030249-v2.0-retry

Bug 1030249 - Notify the server if Find My Device is disabled.
Merge pull request #22227 from davidflanagan/bug1041710-v2.0

Bug 1041710: ensure that wallpaper size always exactly matches screen si...
Merge pull request #21907 from timdream/input-mgmt-get-feature

Bug 1039171 - Runtime decision on whether or not to run preload keyboard oop, r=rudyl
Bug 1016221 - [Collection App] Mozilla CDN Backgrounds for Collection icons
Bug 1029977 - Do not use data-uris for collection backgrounds
Bug 1039311 - [Collection] HomeIcons Singleton (refactor)
Bug 1038578 - [Collection App] Icons are not updated after installing hosted apps from marketplace
Merge pull request #20582 from gitmai/bug-1017356-graphic-defect-settings

Bug 1017356 -Graphic defect in Usage app Settings when Data use alert is...
r=salva
Merge pull request #21033 from vingtetun/2swipe-inprocess

Bug 1027035 - It takes 2 swipes to show the utility tray when you are in...
Merge pull request #21433 from gitmai/bug-1034421-error-widget-msg

Bug 1034421 - [Costcontrol] Costcontrol Widget is not showing proper mes...
r=salva
Merge pull request #21828 from azasypkin/bug-1039585-event-dispatcher

Bug 1039585 - [Messages][Refactoring] Implement EventDispatcher object. r=julien
Conflicts:
	apps/sms/index.html
Merge pull request #21896 from mcjimenez/bug1040375

Bug 1040375 - [SV] do no configure any setting when a valid SIM is not present (r=Fabrice)
Merge pull request #22012 from rnowm/1041779

Bug 1041779 - [Messages][MMS] Download button styles are broken r=azasypkin
Merge pull request #21988 from gitmai/bug-1038810-roaming-customizer

Bug 1038810 - [User Story] Single variant: Data roaming on/off by defaul...
Merge pull request #22114 from eliperelman/bug-1037520-shift-app-launch-start-time-closer-to-user-intent

Bug 1037520 - Include start time capture in the repeat phase, not test start phase r=hub
Merge pull request #22058 from eliperelman/bug-1037520-shift-app-launch-start-time-closer-to-user-intent

Bug 1037520 - Shift app launch start time closer to user intent r=hub,alive