DroidUi: be friendly to Python 3

1. change absolute import to relative import for module
2. change dict.has_key() to key in dict
3. change dict.iteritems() to dict.items()
4. change print statement to print() or warnings
5. use eval() for exec statement
6. use Exception object in raise statement

Signed-off-by: Tommy Alex <iptux7@gmail.com>