Add script for checking coding style

Uses cpplint.py from Chromium depot_tools. Since we all have depot_tools
to build Crosswalk, it is OK to depending on it.

For now all the directories are ignored so we can fix things gradually.
Fix common/ coding style
Fix notification/ coding style
Fix power/ coding style
Fix time/ coding style
Fix network_bearer_selection/ coding style
Fix tizen/ coding style
Add exception for system_info/

SystemInfo makes use of non-const references in its code. Add a filter
to ignore this for now.
Merge pull request #110 from cmarcelo/check-coding-style-script

Check coding style script