Add option to disable status notification

For certain git repositories, this slows down usage
of the shell horifically.

This option can be set with

    git config --add oh-my-zsh.hide-status 1

which will disable checking/showing the status notification

lib/git.zsh

@@ -8,6 +8,7 @@ function git_prompt_info() {
 # Checks if working tree is dirty
 parse_git_dirty() {
   local SUBMODULE_SYNTAX=''
+  if [[ "$(git config --get oh-my-zsh.hide-status)" != "1" ]]; then
     if [[ $POST_1_7_2_GIT -gt 0 ]]; then
           SUBMODULE_SYNTAX="--ignore-submodules=dirty"
     fi
@@ -16,6 +17,7 @@ parse_git_dirty() {
     else
       echo "$ZSH_THEME_GIT_PROMPT_CLEAN"
     fi
+  fi
 }