[Runtime] Register system events information into database during installation.

As is mentioned in https://crosswalk-project.org/jira/browse/XWALK-519,
this PR registers system events at application install time. In detail,
after installation of application pacakge is completed, the main
document will be executed to register the events into system database.
[SysApps] Introduce the SysAppsManager

This class will be the single entry point for registering all
the SysApps extensions. It should be the only class of the "sysapps"
namespace exposed to other subsystems.

In the future it will also manage the lifecycle of data providers (platform
abstractions for extensions like DeviceCapabilities).
[SysApps] Add a "sysapps" master flag

A single flag to disable all the SysApps APIs.
[SysApps] Add unit tests for the SysAppsManager
[Extensions] Fix runtime symbol missing for xesh

Fixes runtime error when building with component=shared_library.

symbol lookup error: libglue_child.so: undefined symbol: HeapProfilerStart
Merge pull request #1364 from tmpsantos/xesh_missing_symbol

[Extensions] Fix runtime symbol missing for xesh
Merge pull request #1235 from shaochangbin/register-system-events

[Runtime] Register system events information into database during installation.
Merge pull request #1357 from tmpsantos/sysapps_manager

[SysApps] Introduce the SysappsManager
Implement DOM screen.lockOrientation and screen.unlockOrientation