Remove * dependency on openssl-sys

Now requires a version between 0.9.0 and 0.11.

Cargo.toml

@@ -9,7 +9,7 @@ links = "pq"
 build = "build.rs"
 
 [dependencies]
-openssl-sys = { version = "*", optional = true }
+openssl-sys = { version = ">=0.9.0,<0.11", optional = true }
 
 [features]
 openssl-static = ["openssl-sys"]