Special case certain keyIdentifier values on linux

This is to work around a chromium bug where these values are
incorrect.
Remove logging of platform
Capitalize Linux
:penguin: Always include shift modifier

The key pressed in not pre-converted on Linux so having the
shift modifier is needed. On Mac OS X pressing cmd-shift-;
would generate cmd-: but on Linux the key identifier is ; in the
event so just return cmd-shift-; as the keystroke.
Merge pull request #10 from atom/ks-key-identifier-on-linux

Special case certain keyIdentifier values on Linux