Upgrade crossterm 0.2 to 0.2.1

Namespaces:
I have changed the namespaces. I found the namsespaces to long so I have shortened them like the following:

Old: crossterm::crossterm_style 
New: crossterm::style

Old: crossterm::crossterm_terminal
New: crossterm::terminal

Old: crossterm::crossterm_cursor 
New: crossterm::cursor

Method names that changed [Issue 4](https://github.com/TimonPost/crossterm/issues/4): 

Old:  crossterm::crossterm_cursor::get();
New:  use crossterm::cursor::cursor();

Old:  crossterm::crossterm_terminal::get();
New:  use crossterm::terminal::terminal();

Old:  crossterm::crossterm_style::color::get();
New:  use crossterm::style::color::color();
