bug 945748 - PageMod.contentScriptWhen tests

test that the PageMod is attached at the right time, depending on the
contentScriptWhen option value.
Added getTabForId
Bug 969739 - A promise chain failed to handle a rejection in the private-browsing-supported add-on test
Bug 944951 - bootstrap.js must remove the added resource: URIs on unload
Bug 908153 removing usage of older openBrowserWindow (which did not wait for focus) and capturing more promise failures
Bug 969774 - isPrivate should accept a nsIChannel
Bug 786998 - test tab events (other than open event) are removed on unload
Bug 964118 - page-mods need a way to alert content-scripts when the add-on in unloaded
Bug 969993 - Raise min/max Versions supported when using --force-mobile
Bug 899747 - Removing use of about:home in tests because the page makes network requests
Bug 966730 - Disabling toggle buttons doesn't work

 - Avoid to set unnecessary state properties
 - Set the toggle on window level by default
 - Added test cases
Merge pull request #1334 from zombie/945748-test-csWhen

fix bug 945748 - PageMod.contentScriptWhen tests @r=ZER0
Bug 935290 - Update sdk/l10n to use .properties files
Merge pull request #1345 from erikvold/935290

Bug 935290 - Update sdk/l10n to support use of packaged `.properties` files r=@gozala
Bug 970145 - Allow `-f` to be used for test add-ons
Merge pull request #1391 from erikvold/969993

Bug 969993 - Raise min/max Versions supported when using --force-mobile r=@jsantell
Bug 951821 - Add test that package.json contributors key works
Merge pull request #1392 from erikvold/951821

Bug 951821 - Add test that package.json contributors key works r=@jsantell
Merge pull request #1384 from erikvold/969739

Bug 969739 - A promise chain failed to handle a rejection in the private-browsing-supported add-on test r=@jsantell
Merge pull request #1387 from erikvold/908153

Bug 908153 removing usage of older openBrowserWindow r=@jsantell