gitfast: fix prompt

Certain themes need the 'clean' mark, and some people like to have the
'dirty' one, just like the original git_promp_info().

We probably shouldn't be modifying that function, there's no other clean
way to achieve our own status information, so let's try to emulate the
original as much as possible.
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>

plugins/gitfast/gitfast.plugin.zsh

@@ -3,5 +3,6 @@ source $dir/../git/git.plugin.zsh
 source $dir/git-prompt.sh
 
 function git_prompt_info() {
-  __git_ps1 "${ZSH_THEME_GIT_PROMPT_PREFIX//\%/%%}%s${ZSH_THEME_GIT_PROMPT_SUFFIX//\%/%%}"
+  dirty="$(parse_git_dirty)"
+  __git_ps1 "${ZSH_THEME_GIT_PROMPT_PREFIX//\%/%%}%s${dirty//\%/%%}${ZSH_THEME_GIT_PROMPT_SUFFIX//\%/%%}"
 }