Set the default shell type to POSIX in vim
Set the default shell type to POSIX in vim

If it can't be determined that a shell script is either `bash` or `ksh`, use `posix` as the default instead of plain `sh`. It seems unlikely that `/bin/sh` wouldn't be a POSIX-compliant shell on modern systems.

See [`:help ft-sh-syntax`](http://vimdoc.sourceforge.net/htmldoc/syntax.html#ft-sh-syntax) and [this thread on /r/vim](https://www.reddit.com/r/vim/comments/25g1sp/why_doesnt_vim_syntax_like_my_shell_files/chlc4ep) for more info.

This fixes the issue where `$(...)` syntax in shell scripts is highlighted as an error in vim.
turino/dotfiles,soon0009/thoughtbot-dotfiles,koerbcm/dotfiles,mspringfield/dotfiles,koerbcm/dotfiles,astoellis/dotfiles,koerbcm/dotfiles,koerbcm/dotfiles,ajkamel/dotfiles,rootulp/dotfiles,moofish32/dotfiles,aliceyoung9/dotfiles,ren/dotfiles,koerbcm/dotfiles,alexbaldwin/dotfiles,voanhduy1512/dotfiles,ransingh/dotfiles,T1D/dotfiles,prabinv/dotfiles,kkelleey/dotfiles,astoellis/dotfiles,Jiwoong/dotfiles,tchiarato/dotfiles,dainmiller/thoughtbot-dotfile-mods,tsigo/dotfiles-thoughtbot,robkilby/dotfiles,soon0009/thoughtbot-dotfiles,aliceyoung9/dotfiles,bschmoker/dotfiles,YepengFan/dotfiles,ransingh/dotfiles,ajkamel/dotfiles,lannn/dotfiles,ecnalyr/dotfiles,bigbam505/dotfiles-work,lannn/dotfiles,ZloeSabo/dotfiles,bschmoker/dotfiles,Danielpk/dotfiles,ren/dotfiles,T1D/dotfiles,tchiarato/dotfiles,ncuesta/dotfiles,kkelleey/dotfiles,bigbam505/dotfiles-work,ransingh/dotfiles,toobulkeh/dotfiles,prabinv/dotfiles,ncuesta/dotfiles,Thau/dotfiles,Jiwoong/dotfiles,YepengFan/dotfiles,mspringfield/dotfiles,dainmiller/thoughtbot-dotfile-mods,Danielpk/dotfiles,Thau/dotfiles,ZloeSabo/dotfiles,moofish32/dotfiles,voanhduy1512/dotfiles,rootulp/dotfiles