level of bot detection

[unixfox]

Because #5 is a bit annoying for visitors, introduce a level of bot detection. Idea of levels of protection:

• 0 : Detect if it's a bot after serving the real HTML code with a basic bot technique
• 1 : Detect if it's a bot before serving the real HTML code with a basic bot technique
• 2 : Detect if it's a bot before serving the real HTML code with an advanced technique like browser fingerprinting