Add rspec filetype.

Since some plugins set filetype of RSpec spec files to rspec, the
filetype has been added to list of types.
The comment string itself is the same as in Ruby files.
Update plugin/NERD_commenter.vim

Add comment delimiters for ConTeXt (the alternative delimiters are for Lua code).
Update plugin/NERD_commenter.vim

Cuda is the same as C.
Remove extra space from Haskell alt.
Merge pull request #97 from johntyree/patch-1

Update plugin/NERD_commenter.vim
Merge pull request #98 from johntyree/patch-2

Remove extra space from Haskell alt.
Merge pull request #91 from sietse/patch-1

Update plugin/NERD_commenter.vim
Merge pull request #79 from DawidJanczak/master

Add rspec flietype