upgrade to native-tls 0.2 + invalid certs (#325)

- Bumps `native-tls` dependency to 0.2 and adapt code accordingly
- Import code used from `tokio-tls` into `connect_async` and adapt dependencies accordinlgy
- Add an option for using `danger_accept_invalid_certs` inside the `Config` struct

Cargo.toml

@@ -18,18 +18,17 @@ encoding_rs = "0.7"
 futures = "0.1.21"
 http = "0.1.5"
 hyper = "0.12.2"
-hyper-tls = "0.2.1"
+hyper-tls = "0.3"
 libflate = "0.1.11"
 log = "0.4"
 mime = "0.3.7"
 mime_guess = "2.0.0-alpha.4"
-native-tls = "0.1.5"
+native-tls = "0.2"
 serde = "1.0"
 serde_json = "1.0"
 serde_urlencoded = "0.5"
 tokio = "0.1.7"
 tokio-io = "0.1"
-tokio-tls = "0.1"
 url = "1.2"
 uuid = { version = "0.6", features = ["v4"] }