Better custom theme loading

oh-my-zsh.sh now also checks for $ZSH_CUSTOM/themes/$ZSH_THEME.zsh-theme when attempting to load a theme. This way custom themes can be a bit more organized in the 'custom' dir

oh-my-zsh.sh

@@ -73,6 +73,9 @@ else
     if [ -f "$ZSH_CUSTOM/$ZSH_THEME.zsh-theme" ]
     then
       source "$ZSH_CUSTOM/$ZSH_THEME.zsh-theme"
+    elif [ -f "$ZSH_CUSTOM/themes/$ZSH_THEME.zsh-theme" ]
+    then
+      source "$ZSH_CUSTOM/themes/$ZSH_THEME.zsh-theme"
     else
       source "$ZSH/themes/$ZSH_THEME.zsh-theme"
     fi