[Package] Implementation of Package API

This patch includes a fully functional implementation of Tizen
Package API. This implemention is dependent on package-manager,
pkgmgr-info and pkgmgr native APIs.

API specification can be found here:
https://developer.tizen.org/dev-guide/2.2.0/org.tizen.web.device.apireference/tizen/package.html

It also includes an example that demonstrates the usage of
Package API.

BUG=XWALK-443
Merge pull request #381 from nagineni/package_api_v2

[Package] Implementation of Tizen Package API