[Android] Add xwalk_core_sample_apk to xwalk_builder

This is the first step to package CrosswalkSample.apk into crosswalk daily release.

BUG=XWALK-1324
[Android] envsetup: Stop unsetting CHROMIUM_GYP_FILE.

This is one step towards simplifying our envsetup.sh. Chromium stopped
touching CHROMIUM_GYP_FILE in r248748, and it is safe for us to do the
same.
Merge pull request #1873 from kurli/package-crosswalk-sample

[Android] Add xwalk_core_sample_apk to xwalk_builder
[Runtime] Add locale logic to runner, and implement locale for tizen.

Add a class TizenLocaleListener to listen and get the
locale of tizen.

Move
runtime/browser/xwalk_runner_tizen.cc
runtime/browser/xwalk_runner_tizen.h
because tizen runner need tizen locale listener who depend
on vconf, and vconf only used on tizen.

We need refresh name on the dbus when application locale
is changed(because we may get a new name on new locale).
Merge pull request #1874 from rakuco/no-unset-chromium_gyp_file

[Android] envsetup: Stop unsetting CHROMIUM_GYP_FILE.
Merge pull request #1836 from yeyuyinjie/system_locale

[Runtime] Add application locale to application system
[Runtime] Add i18n support for widget

Manifest will prase i18n item, and we can get i18n string
from GetString

Finish the todo so that we can get a locale name or
description when locale is changed.