[Android] Use ant and xwalk_core_library for make_apk

Previously, we are copying the python script from gyp
and reproduce the steps gyp generated to build
xwalk_app_template_apk to make apk.

It's hard to maintain and now xwalk_core_library is
mature enough to be used as Android Library Project.

This commit uses ant and xwalk_core_library to make
apk to replace previous approach.

The changes including:
1. The app packaging tool structure:
 a. Assets, jars and template code are now put in
    "template", jars includes xwalk_runtime_java
    and xwalk_app_runtime_java.
 b. xwalk_core_library will be put in root folder of
    packaging tool.
 c. Scripts used by gyp generated commands are removed.
2. When make apk:
 a. Embedded Mode:
  1) Copy template to app folder named according to
     input app name.
  2) Copy xwalk_core_library into app folder.
  3) Move arch folders under "app/xwalk_core_library/libs/"
     to "app/native_libs/<arch>"
  4) For each target arch:
   4.1) Run "android update lib-project" for app/xwalk_core_library.
   4.2) Run "android update project" for app.
   4.3) Remove all subfolder in "app/xwalk_core_library/libs",
        to make sure it will only contains one arch folder after 4.4).
   4.4) Move back the needed native library for target arch back.
        it's actually partly reverting step 3).
   4.5) Run "ant release" in app.
   4.6) Copy and rename the built apk out to root folder of
        packaging tool.
 b. Shared Mode:
   1) Copy template to app folder named according to
      input app name.
   2) Remove xwalk_runtime_java.jar in "app/libs".
   3) Run "android update project" for app
   5) Run "ant release" in app.
   6) Copy and rename the built apk out to root folder of packaging
      tool.

BUG=https://crosswalk-project.org/jira/browse/XWALK-2128
[Android] Passwords of keystore as argument should not be mandatory

When make apk, if user wants to use their own keystore, they must
provide the password as command line argument for now.
Developers may have security concern for this.

This commit allows developers to input password while making apk.

BUG=https://crosswalk-project.org/jira/browse/XWALK-2138
[Tizen][Runtime] Fix unable to launch from a url.

The xwalk-launcher can not launch an application from a url, because of using a
wrong entry point. This patch will solve this, using the entry point
"StartURLKey" instead.

BUG=XWALK-2171
[Android] Add target to generate AAR library

use command "ninja -C out/Release xwalk_core_library_aar" can generate AAR library,
the construct of this library is Root/jni/so Root/res Root/classes.jar Root/R.txt
Root/AndroidManifest.xml
the AAR library test successfully by gradle with different architecture.

BUG=XWALK-1930
Merge pull request #2284 from takethathe/fix-xwalk-2171

[Tizen][Runtime] Fix unable to launch from a url.
Merge pull request #2270 from fujunwei/aar-library

[Android] Add target to generate AAR library
Merge pull request #2229 from wang16/ant_make_apk

[Android] Use ant and xwalk_core_library for make_apk
[Tools] Remove packaging/.

These scripts for creating Crosswalk installers were never used for
anything, contain unlicensed files are just dead weight.
Merge pull request #2288 from rakuco/remove-packaging-tools

[Tools] Remove packaging/.