[Android] Specify valid characters and verify app name.

This patch is to specify valid characters and verify the app name
in customize.py
Specify the valid characters, if the app name or package name is invalid,
provide the error information and advice.
Add test cases for invalid chars.

BUG=https://crosswalk-project.org/jira/browse/XWALK-1298
Merge pull request #1826 from wuhengzhi/character_handling

[Android] Replace invalid characters and verify app name.