String: performance improvement converting uint64_t to string (4x)

Based on the trick given by A. Alexandrescu on Facebook Engineering
blog, this patch replace the old mk_str_itop() with the faster
algorithm proposed.

More details about the implementation here:

 https://www.facebook.com/notes/facebook-engineering/three-optimization-tips-for-c/10151361643253920

Signed-off-by: Eduardo Silva <eduardo@monkey.io>
README.md: removed identi.ca link

The link gives only an error message.
Merge pull request #161 from txt-file/patch-1

identi.ca
Epoll: initialize unitilialized static epoll event

Signed-off-by: Eduardo Silva <eduardo@monkey.io>