Reexport pairing.

Since we are reexporting some of the pairing types, we should also
export pairing itself, to make all the matching traits available and
avoid version conflicts.

src/lib.rs

@@ -14,7 +14,7 @@ extern crate lazy_static;
 #[macro_use]
 extern crate log;
 extern crate memsec;
-extern crate pairing;
+pub extern crate pairing;
 extern crate rand;
 #[macro_use]
 extern crate rand_derive;