[Android] Keep package path for the generated java files

It will be convenient for IDE like eclipse to debug for
those source files.
[REG] Fixed NaCl loading issue introduced by rebase.

According to the upstream change 01167110, the trusted plugin is
linked into the renderer directly instead of loading as a module
in runtime, and the ppGoogleNaClPlugin module has been removed;
so we need to change the plugin loading codes in
XWalkContentClient::AddPepperPlugins.
Reinstall option of backend

This commit adds "-r" option for xwalkctl.
xwalkctl may be called with this option by package manager to reinstall app in specific way may be implemented later.

For now, we need just to signal pkgmgr that reinstallation fails to prevent hanging requesting process.

TASK=XWALK-2458
[Android] Add xwalk_app_template_apk to xwalk_app_template's dependency

xwalk_app_template_apk is to verify the correctness of xwalk_app_template
before creating the package of it.
Set the dependency although, xwalk_app_template doesn't rely on
xwalk_app_template_apk to build.
Merge pull request #2393 from jondong/naclLoading

[REG] Fixed NaCl loading issue introduced by rebase.
Merge pull request #2396 from tiwanek/XWALK-2458

[Tizen] Reinstall option of backend
Merge pull request #2388 from wang16/reflection_layer

[Android] Keep package path for the generated java files
Merge pull request #2386 from wang16/template_apk

[Android] Add xwalk_app_template_apk to xwalk_app_template's dependency
[Android] Use reflection layer in xwalk core for runtime usage

As now there is reflection layer between xwalk core and xwalk
core internal, there is no need to use the one between runtime
and runtime client for runtime usage.

After this patch, most facilities to support shared mode will be
moved from runtime to xwalk core. Besides, runtime_java will be
merged into runtime_client_java.
XWalkRuntimeLib.apk will keep the name unchanged, but its package
will be org.xwalk.core which was org.xwalk.runtime.lib previously.

TODO: Extension is still using reflection in runtime layer which
will be refined in future commits.
[Android] Move extension manager out to runtime layer

Extension in runtime layer (XWalkExtensionClient) was
directly using XWalkExtensionAndroid, which has core
internal dependency.
It should be based on the extension provide by xwalk
core.
Move all the classes for runtime extension to runtime
client package and remove the reflection layer which
is not between XWalkExtension and XWalkExtensionInternal.