[Android] Improve error messages for runtime and packaging tool

Fix https://crosswalk-project.org/jira/browse/XWALK-1283 issue 2.
Show x86/arm architectures after building. like below:
WARNING: This APK will only work on x86/ARM based android devices"
Consider building for ARM/x86 as well.
Merge pull request #1763 from jinbang/improve_error_messages

[Android] Improve error messages for runtime and packaging tool