[Android] Implement runtime client with runtime library embedded

We should support both shared and embedded mode for runtime
client to use runtime library, which providing java class, native
lib and pak resources for runtime client.

Currently, only shared mode is implemented. In shared mode,
runtime library is an Android app.

This commit implements an alternative to allow packing runtime lib
embedded in runtime client. The api will stay unchanged and the
client of runtimeView will not aware the difference.

Add a new target, xwalk_runtime_client_embedded_shell, which is
the shell using runtime view with library embeded. It's for
testing purpose.

TODO=https://github.com/crosswalk-project/crosswalk/issues/657
BUG=https://github.com/crosswalk-project/crosswalk/issues/640
[Android] Pack the files needed by app template for embedded mode

To create an app using embed mode of runtime library.
It needs the relevant java class, native library and assets.

Copy them in target prepare_xwalk_app_template so that
they will included in generated tarball of app template.

BUG=https://github.com/crosswalk-project/crosswalk/issues/657
[Android] Use 'jsapi' instead of 'js_api' in extensions-config.json

Let's keep the consistency of using the jsapi. No need of '_'.
XWalkExtensionClient: do not warn in expected situations

Once XWalkExtensionClient decides to destroy an instance, it deletes
it but keeps it's id around waiting for server confirmation. The id is
associated with a NULL instance in the map.

When we send the DestroyInstance message to the server, it's already
marked that way in the client. So we may receive a pending PostMessage
from the server. In this case, we shouldn't warn, but simply ignore,
since there's no JS to send the message anymore.

We keep the warning for the case where after server confirmed the
destruction, we get another message. This will indicate a real problem
either in extension implementation or in the system.
Merge pull request #760 from cmarcelo/dont-warn-for-pending-message

XWalkExtensionClient: do not warn in expected situations
Bump version to 1.29.8.0
Merge branch 'master' of github.com:crosswalk-project/crosswalk
Merge pull request #759 from yongsheng/smallfix

[Android] Use 'jsapi' instead of 'js_api' in extensions-config.json
Merge pull request #658 from wang16/embed

[Android] Implement runtime client with runtime library embedded
[Android] Remove js_api as the input path of hello world app

Js_api folder in assets was already removed in #668.
Merge pull request #695 from ShDavidliu/master

[Android] Implement default xwalk client in runtime core.
Merge pull request #764 from wang16/fix_js_api

[Android] Fix a missed place when renaming js_api to jsapi
[Android] Update the manifest json parser as the changed field of "app".
1 Retrieve the field of "app" in manifest.json.
2 Retrieve the field of "launch" in the value of "app".
3 Retrieve the filed of "local_path" in the value of "launch".
4 Get the value of "local_path".

BUG=#778