Add %membership_level% template tag support on restricted content message

[ashleyfae]

This would identify which membership level the current post is restricted to and replace %membership_level% with the name of that level.

This would only work if "restrict to specific level(s)" is used in restrictions.

[mihaijoldis]

Here is what the customer replied back to me about when a post would be restricted to more than 1 level

if post is "restricted to multiple levels at a time" it should show easily only information "this post is for members on $20 tier or higher".