Fix cipher-aes128 build issue in GHC 7.6.4.

The twitter-conduit package has an indirect dependency on cipher-aes128.
The newest version of cipher-aes128 is 0.7.0.1, but it rejected by
solver when using GHC 7.6.4:

~~~~
[196] next goal: cipher-aes128 (dependency of DRBG-0.5.4)
[196] rejecting: cipher-aes128-0.7.0.1 (conflict: binary => bytestring==0.10.0.2/installed-4f9..., cipher-aes128 => bytestring>=0.10.2)
[196] trying: cipher-aes128-0.7
[197] trying: cipher-aes128-0.7:!bench
~~~~

twitter-conduit.cabal

@@ -65,7 +65,7 @@ library
     , aeson >= 0.7.0.5
     , attoparsec >= 0.10
     , data-default >= 0.3
-    , bytestring >= 0.9
+    , bytestring >= 0.10.2
     , text >= 0.11
     , containers
     , time