Trim down default data

[tsvetomir]

The goal here is to allow basic function of the library in en-US with minimal data.

To that end I've included a minimal likelySubtags and currencyData.

@danielkaradachki suggested that we can trim weekData as well. We can only leave:

"weekData": {
    "firstDay": {
        "001": "mon",
        "US": "sun"
     }
}

And we can trim down currencies even more. Before you ask, BGN is used in the tests as a non-default currency :)

"currencies": {
    "BGN": {
        "displayName": "Bulgarian Lev",
        "displayName-count-one": "Bulgarian lev",
        "displayName-count-other": "Bulgarian leva",
        "symbol": "BGN"
    },
    "USD": {
        "displayName": "US Dollar",
        "displayName-count-one": "US dollar",
        "displayName-count-other": "US dollars",
        "symbol": "$",
        "symbol-alt-narrow": "$"
    }
}