[Runtime] Add XPK package generate tool

The python script can generate XPK package from Crosswalk application
resources, furthermore, it will generate a RSA private key if it's invalid.
[Tizen] Polish Python code according to Chromium Python style guidelines.

Per Chromium Python style guidelines,
http://www.chromium.org/chromium-os/python-style-guidelines
This CL sets single quote for string values, and sets functions names
with CapWords() style.
[Tizen] Enable pkginfo uninstall for Tizen.

This CL supports to uninstall package information from Tizen Database,
as well as remove application icons, execute path and XML file from Tizen system.

As for the python script arguments, the --install option will not take
values any more, also a new option --uninstall is added to support
uninstall package information from Tizen.

For class InstallHelper() in Python, the parameter input_path is removed from
constructor, because it could be generated by the other parameters.
Also several class member variables are added, e.g, icon_path_ , execute_path_,
which could be shared by install and uninstall functions.

Besides, we found the issue that application icon could not display on home
screen if package name contains white spaces. To fix this issue, the installer
script strips these whitespaces when writing package information into database.
Merge pull request #665 from shaochangbin/cb-uninstall

[Tizen] Enable pkginfo uninstall for Tizen.
Merge pull request #669 from takethathe/generator

[Runtime] Add XPK package generate tool
[Extensions] Fix Zombie extension process on Linux after a ctrl+c

On Linux we are currently leaving the extension process alive
even after its parent, the BrowserProcess, was killed with ctrl+c
(^C, or SIGTERM).

We still haven't found a more chromium-ish way of doing this,
so let's stick to prctl.h for now.
[Extensions] Change switch to --disable-extension--process

This will enable the ExtensionProcess (EP) by default for all
platforms, but shouldn't affect Android. On this platform,
XWalkExtensionService::RegisterExtension is called directly,
which makes extensions to be registered on the in_process
XWalkExtensionServer.
[Extensions][Android] Disable ExtensionProcess by default
[Extensions][Tests] Make ExternalExtension tests use the ExtensionProcess