add command to force a syntastic check
add command to force a syntastic check

This allows a particular file type to be disabled but still be checked
when desired.  Useful for syntax checks that take a few seconds like the
puppet one.

wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup,wezhang/vim-setup,nikmartin/dotfiles,wezhang/vim-setup,wezhang/vim-setup