[Remove dependencies] Convert some default format to external package

[A-312]

With lerna a github repo could have several npm package see this repo. And we can get this folder structure :

packages/
# validator
packages/ipaddress/
packages/email/
packages/url/
# moment.js
packages/duration/
packages/timestamp/
test/
lib/
...
package.json

I propose to outsource format using validator and moment.js (#317) according to #303 (comment).

We have to replace this line : https://github.com/mozilla/node-convict/blob/master/lib/convict.js#L213 I think we can use directly indexOf because 'x' must be a string and this is enough for string value !