Bug 1035718 - [FTU] - remove unused images
Bug 994571 - [System2] Remove the pattern to return self in start()

* Remove 'var module = new Module().start()' pattern.
* Remove 'return this;' expression in start() function definitions.
Bug 1040091 - [v2.1] Fix imei issue in test_settings_device_info.py
Bug 1038671 - Ignore the hardware home button when the software one is enabled.
Bug 1034985 - Prevent switch notification to show up for inactive preloaded attention screens.
Bug 1029721 - CDMA call waiting call is not logged in call history
Bug 1040070 - [Verical Homescreen] Use smaller images sizes for low capability devices r=crdlc

The following changes are made for low capability devices:

* Icons default to 4 per row.
* Icon resolution is reduced.
* Icon rendering does not account for devicePixelRatio.
Bug 1039171 - Runtime decision on whether or not to run preload keyboard oop
Merge pull request #21734 from pivanov/bug-1035718

Bug 1035718 - [FTU] - remove unused images
Merge pull request #21603 from begeeben/994571_remove_the_pattern

Bug 994571 - [System2] Remove the pattern to return self in start(), r=alive
Revert "Bug 1036236 - [LockScreen] Unlock to Camera twice would make it unavailable" for breaking gaia unit tests

This reverts commit c602a44b7077670b50f6627e305cf149c594370d.
Merge pull request #21762 from etiennesegonzac/bug-1038671

Bug 1038671 - Ignore the hardware home button when the software one is enabled r=21
Merge pull request #21759 from etiennesegonzac/bug-1034985

Bug 1034985 - Prevent switch notification to show up for inactive preloaded attention screens r=21
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
Merge pull request #21638 from tamarahills/bugfix/1029721

Gaia fix for placing cdma call waiting call in the call log r=gsvelto
Merge pull request #21834 from KevinGrandon/bug_1029902_low_memory_features

Bug 1029902 - [Vertical Homescreen] Implement device capability configuration
Merge pull request #21874 from chirarobert/fix_imei_test

Bug 1040091 - [v2.1] Fix imei issue in test_settings_device_info.py
Bug 1038103 - Generate documentation from source code and publish to readthedocs.org. r=wlachance r=zcampbell
Bug 1039585 - [Messages][Refactoring] Implement EventDispatcher object. r=julien