Fix for https://github.com/eagletmt/ghcmod-vim/issues/30

A fix is to explicitly tell ghc-mod to use newline as the line separator, in place of its default NULL.  The requisite flag ("-b") is present in ghc-mod >= 2.1.2.

As I understand it, the issue is the result of ghc-mod issues/changes
- https://github.com/kazu-yamamoto/ghc-mod/issues/128
- https://github.com/kazu-yamamoto/ghc-mod/issues/92
In short: GHC 7.6 is sending the splices to ghc-mod via the logger rather than stderr, so that ghc-mod is inserting its own default line separator (NULL) rather than passing on GHC's.