doc: fix blog link in blog posts and README

Apparently Joyent decommissioned joyeur.com but at least they saved the
contents of the blog.  Update the links in the README and the nodejs.org
blog posts.

Hat tip to Eugen Pirogoff (@eugenpirogoff) for pointing it out.

Fixes #6224.
tls: don't push() incoming data when ondata is set

Otherwise the data ends up "on the wire" twice, and
switching between consuming the stream using `ondata`
vs. `read()` would yield duplicate data, which was bad.
doc: specify the format of the `ca` tls option
doc: fix typos in the tls `NPNProtocols` option
doc: document reserved status of SIGUSR1

Fixes #1212.
readline: handle input starting with control chars

Handle control characters only when there is a single byte in the
stream, otherwise fall through to the standard multibyte handling.
uv: Upgrade to v0.10.17
2013.09.24, Version 0.10.19 (Stable)

* uv: Upgrade to v0.10.17

* npm: upgrade to 1.3.11

* readline: handle input starting with control chars (Eric Schrock)

* configure: add mips-float-abi (soft, hard) option (Andrei Sedoi)

* stream: objectMode transforms allow falsey values (isaacs)

* tls: prevent duplicate values returned from read (Nathan Rajlich)

* tls: NPN protocols are now local to connections (Fedor Indutny)
Merge branch 'v0.10.19-release' into v0.10
Now working on 0.10.20
blog: Post for v0.10.19
blog: add missing shasums for v0.10.19 release
doc: add asynchronous execution example