[IVI][Runtime] Fix unable to install application on Tizen IVI 3.0 image.

The package install/uninstall/update for Tizen are designed to integrate
with AMD (Application Management Daemon) on Tizen mobile 2.x, not
compatible with Tizen IVI 3.0.

This is a temporary solution to revert to use macro OS_TIZEN_MOBILE, this
means install/uninstall/update won't work with AMD on Tizen IVI. We'll
add that support back later.

BUG=XWALK-1074
Merge pull request #1661 from takethathe/ivi_bug_1074

[IVI][Runtime] Fix for installing application on Tizen IVI 3.0 image.
[Runtime] Fix launch issue for widget applications that don't have
'content' element in config.xml.

Per Widget spec, the occurrences of 'content' element can be zero or one.
If there is no 'content' in config.xml, we should still be able to launch
widget application by the default 'index.html' path

BUG=XWALK-1109