Bug 1008187 - [Camera] Update to use <gaia-header>
Merge pull request #19865 from wilsonpage/1008187

Bug 1008187 - [Camera] Update to use <gaia-header>
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.