More randomness, and without md5

From 100000000000000 possibilities to 5316911983139663491615228241121378304, witch is a bit more :)

According to https://en.wikipedia.org/wiki/Universally_unique_identifier#Random_UUID_probability_of_duplicates

For 2^36 files, probability of collision is 0.0000000000000004
With old method, probably was 0.99999999983382806 :(