Parse configuration at compile time in tests

[Thomasdezeeuw]

Currently all end-to-end tests (in the tests directory) have various constants, such as:

stored/tests/http/post.rs

Lines 9 to 11 in cebe268

	const DB_PORT: u16 = 9002;
	const DB_PATH: &'static str = "/tmp/stored_post_tests.db";
	const CONF_PATH: &'static str = "tests/config/post.toml";

These must match the configuration as defined in the files (in tests/config). Keeping this in check is a bit of hazard. It would be could if we could parse it at compile this and set the constants to the correct values. Or even have the entire Config structure as a constant.