concurrency patterns
Update 2013-12-07-concurrency-patterns.md

corrected a couple of typos, and incorrect use of it's
Merge pull request #37 from dereke/patch-1

Update 2013-12-07-concurrency-patterns.md
suggestions from @artemave
fixed typo
typo spotted by @adiel
removed IO primer

* added JavaScript example to sequence
* removed fire and forget for one function

(thanks @artemave + @joshski)