The closest I could get was xenophile. Also, optimistic would be a close second and I say that because I don't think that optimistic is a better description than xenophile because xenophile actually includes love.
Omniphile: omni = every; -phile = love. Xeno- = foreign things, so xenophile means lover of foreign things, not lover of everything.
Besides the already-offered neologism omniphile, consider Pollyanna:
One who is persistently cheerful and optimistic, even when given cause not to be so. [eg] You call her an optimist, but I call her an obnoxious Pollyanna.