[Tizen][Extensions] Implemented W3C SysApps Device Capabilities API

The implementation is based on 17 October 2013 editor draft version.
CPU, Memory, Storage and Display are included, the Audio and Video Codecs
are not implemented yet.

sysapps/device_capabilities/device_capabilities_api.js will be shared by Android and Tizen. (Here, I haven't remove the js file in case that the build fails. Once the https://github.com/crosswalk-project/crosswalk/pull/961 is merged. The js file will be replaced.

Tizen and Android will share the same test case which locates in app/android/runtime_client_shell/assets/device_capabilities.html through https://github.com/crosswalk-project/crosswalk/pull/961.

SPEC=http://www.w3.org/2012/sysapps/device-capabilities/
BUG=https://crosswalk-project.org/jira/browse/XWALK-47