screenrc: system clipboard usage

* Add possibility of copying from screen's copy buffer to X's clipboard.
  To use, install xsel and uncomment the relevant line in screenrc.

Signed-off-by: Adrian-Tudor Panescu <adrian@panescu.com>
vimrc: system clipboard usage

* Use xsel for accessing system clipboard.

Signed-off-by: Adrian-Tudor Panescu <adrian@panescu.com>
vimrc: filetype fixes

* Move filetype options after Vundles.

* Disable plugin by default to avoid git commit messages auto-indent issues.

Signed-off-by: Adrian-Tudor Panescu <adrian@panescu.com>