[Android] Remove the Android SDK dependency for packaging tool

With this patch, if environment variable "PACKAGE_WITH_DEPENDENT_TOOLS" is
assigned as "True", the "xwalk_app_template" will be packaged with Android
SDK tools dependent by "make_apk.py", so users don't need to download Android
SDK to use "make_apk.py".

Only necessary libs&tools will be copied from Android SDK of xwalk building machine,
it includes:
(1) ANDROID_SDK_PATH/build-tools
(2) ANDROID_SDK_PATH/platforms/platforms/android-19/android.jar
(3) ANDROID_SDK_PATH/tools. Only necessary libs&tools needed by "make_apk.py" are
cppied. The file "tools-list.txt" includes the list of those libs&tools.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1258
`FindSdkPath`