fixing custom formats by string

[caridy]

This PR fixes the option to pass a second argument as string to select a custom formatter:

{{intlNumber NUM "foo"}}
{{intlDate 1390518044403 "bar"}}

It also fixes the message format for something like this:

the cost {price, number, foo} will be ready by {deadline, date, bar}

where foo is a number formatter, and bar is a data formatter.

[yahoocla]

CLA is valid!

[drewfish]

+1

[caridy]

+v0.1.0