[Android] Check webview legacy api for external protocol handling first

Crosswalk provides two ways for embedders to extend protocol handling.
1. The same api as legacy webview api in XWalkContentsClient,
   shouldOverrideUrlLoading().
2. Extends XWalkNavigationHandler.

By default, xwalk doesn't do anything in shouldOverrideUrlLoading, but
handles action uri in XWalkNavigationHandler.
To avoid the case that some embedder override shouldOverrideUrlLoading
in the way conflicts with what xwalk already did in XWalkNavigationHandler,
calling shouldOverrideUrlLoading prior to invoke XWalkNavigationHandler
so that embedders won't get confused.

BUG=https://crosswalk-project.org/jira/browse/XWALK-654
[Android] Add arch option for packaging tool in embedded mode.

Accept the arch option from developer for embedded mode. if the arch
option is unspecified, all available platform apks will be generated.

Usage: python make_apk.py --arch=x86 ...

BUG=https://crosswalk-project.org/jira/browse/XWALK-598
[Android] Correct the error message for embedded sample app

Change to more general term:
"Crosswalk failed to initialize."
The detail information about the failure will be shown in
the pop up dialog.

BUG=https://crosswalk-project.org/jira/browse/XWALK-649
[Android] Add the check of application launch path in packaging tool.

   Since there is no prompt when there is no application launch path
in the manifest.json file, to improve the user experience of crosswalk,
in the packaging tool, add the check of application launch path in packaging
tool. The related test case is added.

BUG=https://crosswalk-project.org/jira/browse/XWALK-645
Merge pull request #1253 from junmin-zhu/arch

[Android] Add arch option for packaging tool in embedded mode.
Merge pull request #1287 from qjia7/master

[SysApps][Tizen] Fixed the incorrect event type and rename the event type
Merge pull request #1303 from zliang7/dev

[Tizen] Fix screen rotates regardless "auto rotate" setting
[Android] Update the user interface of http authentication dialog.

  Update the text margin and the string of http authentication dialog.

BUG=https://crosswalk-project.org/jira/browse/XWALK-646
Query the number of presentation displays when extension is created.

In some case, e.g. in cordova container, onResume method won't get
called at startup, it is called only when resuming from background
status.

This fix can make sure that presentation.displayavailable flag won't
depend on the fact if PresentationExtension::onResume gets executed.
[SysApps] Fix bug when adding a method that returns a Promise

The BindingObject should create a Promise for every method call. The
current code was using the same instance for every call and it will
obviously fail after the first method invocation.

Also update the tests so it would have caught the bug in the first place.
Merge pull request #1312 from tmpsantos/promise_method_fix

[SysApps] Fix bug when adding a method that returns a Promise
[Android] Put app resource in sub directory of assets

Before this all app resources are put in assets, which may cause
confliction with other resources(of runtime, extensions etc).
So we define a sub directory "www" to put the app resources
instead.

BUG=https://crosswalk-project.org/jira/browse/XWALK-174
Launch xwalk with the current orientation (not portrait)

Without this bug fix, xwalk will always launch in portrait-primary
and never rotate to the correct orientation, as it internally
doesn't consider to be in portrait-primary.
Merge pull request #1315 from kenchris/chorientation

Launch xwalk with the current orientation (not portrait)
Add a --list-features-flag command line argument to dump the features flags.

- Add a DumpFeaturesFlags to output this in the terminal.

- Fix on the way the "enable-experimental-features" string and declare
it properly in the XWalk switches.
Style fix of the vector containing the features flags.

... So that it matches the Chromium style.
Use xwalk_switches for "enable-xwalk-experimental-features"

to follow the rest of the command line arguments.
Merge pull request #1316 from darktears/list-runtime-features

List runtime features with "--list-runtime-features" from the command line.
Port the XWalkRuntimeFeatures class to use the Singleton<> pattern
of Chromium.

So we're a bit align with Chromium code.
Merge pull request #1317 from darktears/runtime-features-singleton

Port the XWalkRuntimeFeatures class to use the Singleton<> pattern