Add EventStream.flatMapError
Add Bacon.error convenience function that sends an error and ends

Bacon.once's evil cousin ]:->
Add Bacon.retry
Allow interval by context
Remove everything related to isValidValue from Bacon.retry

Similar effect can (and should) be implemented in the client code,
by transforming the source stream as suggested by @jonifreeman:

Bacon.retry({source: someSource.flatMap(function(x) { return x === "FOO" ? Bacon.error("invalid value") : Bacon.once(x) })})
Merge branch 'retry' of https://github.com/mileskin/bacon.js into mileskin-retry
simplify, include toString
fix Bacon.retry toString
Merge branch 'mileskin-retry'
update relnotes
remove Bacon.error as duplicate for Bacon.once(new Bacon.Error())
Fix typo in "README.md"
Merge pull request #371 from JustBlackBird/20140518_fix_typo

Fix typo in "README.md"
Fixed typo in readme-src.coffee
make merge based on mergeAll and not vice-versa
update relnotes
release 0.7.12
Updated Bacon.js NuGet Package to 0.7.12 (and readme link)