Change version vow.js 0.3.0 -> 0.3.12

in node 0.10 domains dont bind to callbacks passed to `then` etc.
error occurs in vow.js version 0.3.0
vow 0.3.12 fixes this bug using `setImmediate` instead of `process.nextTick`

Tests:
https://github.com/gkrasulya/vow-0-3-0-test
https://github.com/gkrasulya/vow-0-3-12-test

Bug occurs only with node >=0.9 because of changes in `process.nextTick`
Merge pull request #140 from gkrasulya/master

Node 0.10, Vow.js 0.3.0, domains don't bind to callbacks passed to `Vow.then`