Update submodule vim/bundle/ack 0dd636e...f8d518a

* vim/bundle/ack 0dd636e...f8d518a (35):
  > Merge pull request #116 from brianpeiris/patch-1
  > back with information about special chars on readme
  > put space between ackprg and ack_default_options :bomb:
  > fixes #109, replace eval by str2nr
  > only apply maps when found results
  > do not blow without ack or ack-grep
  > add documentation for g:ackpreview
  > fix other maps to work only on quickfix window
  > fix maps to work only on quickfix window
  > fix highlight, force to highlight the searched term
  > Merge pull request #107 from juanpabloaj/noinstalled
  > update version goals
  > Remove `ack_wildignore` feature.
  > fixes #105. Fix wildignore with "dir/**" values
  > Avoid conflict with ag
  > add information about how use ag with ack.vim
  > update README goals DONE
  > improve documentation about wildignore
  > fix wildignore to ignore directories too
  > By default ignore files listed on wildignore
  > Remove support for rake install
  > add as goal for 1.0 use autoload directory
  > add a link for ack documentation
  > add a little RoadMap plan
  > You can use more than one directory as parameter
  > improve installation section
  > remove ack installation steps, just linked it with the official manual
  > just improve indentation an update ack url
  > add documentation for g:ackprg
  > add documentation for ackhighlight
  > Merge pull request #83 from zmughal/fix/ack-2.0-args
  > manually add #86 diff. closes #86
  > Merge branch 'mMontu-master'
  > Merge pull request #77 from thebinarypenguin/auto-preview
  < Merge remote-tracking branch 'upstream/master'