Deep object merging

[sailorgeoffrey]

As config is basically a tree of maps, we should be able to merge configurations at. multiple levels. For example common config in default.json should be merged with envy specific config in staging. Jason

Default.json:
{
db: {
driver: "MySQL"
}
}

Staging.json:
{
db: {
host: "staging.foo.com"
}
}

config.get("db") == {
host: "staging.foo.com",
driver: "MySQL"
}

For simplicity matching keys can be overwritten.