Add better vim integration to readme

Add instructions to integrate into vim such that it runs stylish-haskell automatically whenever you save a .hs file.
Update README.markdown
Merge pull request #56 from nbouscal/patch-1

Add better vim integration to readme
Reference vim-stylish-haskell in VIM integration
Merge pull request #58 from nbouscal/patch-1

Reference vim-stylish-haskell in VIM integration
Fix language pragma compact_line test
Allow haskell-src-exts 1.15
Utrecht style language pragmas
Group import settings puts qualified imports at the bottom, doesn't align import lists, and aligns `as` by only looking at the names of the qualified imports, also sorts imports case sensitively
Remove padding before unqualified import lists