[Android] Add test cases for XWalkJavascriptResult.

This patch is to add test cases for the interfaces in
XWalkJavascriptResultInternal.java.
[Android] Fix that getBridge() method will be in javadoc

getBridge() is for internal to use, should not be public.
Update the generator script.
[Android] Embedding API 3.0: XWalkPreferences

Add following APIs:
public static final String JAVASCRIPT_CAN_OPEN_WINDOW;
public static final String ALLOW_UNIVERSAL_ACCESS_FROM_FILE;
public static final String SUPPORT_MULTIPLE_WINDOWS
public static void setValue(String key, String value);
public static void setValue(String key, int value);
public static boolean getBooleanValue(String key);
public static String getStringValue(String key);
public static int getIntegerValue(String key);

Deprecated API:
public static boolean getValue(String key);

BUG=https://crosswalk-project.org/jira/browse/XWALK-2376
[Android] Add support of getting mime type for app url scheme.

This patch is to add support of getting mime type for app url scheme.
As crosswalk supports app scheme and the local path in "iframe" was
loaded with "app://", so add conditional to get the related mime type.
The app scheme was removed in commit
12b98a890de27d1ec96eb7f10558010fc7412e58.

BUG=XWALK-2300, XWALK-2301
[Android] Add onStart and onStop to XWalkExtensionClient

Added the onStart() and onStop() method in XWalkExtensionClient,
and also added these two functions in the related classes to
make it work for XWalkExtensionClient. Now extension developer
can override the onStart() and onStop() when the activity's
onStart() and onStop() get triggered.

BUG=XWALK-1708
Merge pull request #2383 from wuhengzhi/backgroud_with_no_instrinsic_size

[Android] Add support of getting mime type for app url scheme.
Merge pull request #2353 from wang16/reflection_layer

[Android] Fix that getBridge() method will be in javadoc
Merge pull request #2372 from jondong/onStart

[Android] Add onStart and onStop to XWalkExtensionClient
[Runtime] Add "-c" option for xwalkctl for restarting aborted install/update tasks.

Crosswalk runtime should have a mechanism to restart the aborted install or
update tasks which are stopped by accident like power off. This patch related to
bug: https://crosswalk-project.org/jira/browse/XWALK-1565

How to use:
========
$ xwalkctl --continue
Merge pull request #2341 from wuhengzhi/xwalk_js_result_test

[Android] Add test cases for XWalkJavascriptResult.
Merge pull request #2375 from takethathe/restart_task

[Runtime] Add "-c" option for xwalkctl for restarting aborted install/update tasks
Multi user features :

->Use Usr App related fonctions instead of Global App related Functions
->Manage properly icon path for each user

BUG=XWALK-2249

Change-Id: I5be59d0264aed84f708273b58061c8834dd63404
Signed-off-by: Sabera Djelti (sdi2) <sabera.djelti@open.eurogiciel.org>
Signed-off-by: Baptiste DURAND <baptiste.durand@open.eurogiciel.org>
Merge pull request #2298 from eurogiciel-oss/multiuser_xwalk_2249

Multi user features :
Merge pull request #2354 from wang16/embedding_api_3

[Android] Embedding API 3.0: XWalkPreferences