Use crypton instead of cryptonite

This also requires updating dependencies to use crypton.

Unfortunately, cryptostore will only use crypton if the use_crypton
Cabal flag is enabled, and we can't make that happen from our cabal
file. I opened an issue to ask them to remove `manual: True` from their
flag, so that the solver can try enabling it. See:
ocheron/cryptostore#13

jwt.cabal

@@ -33,7 +33,7 @@ library
   exposed-modules:     Web.JWT
   other-modules:       Data.Text.Extended, Data.ByteString.Extended
   build-depends:       base >= 4.8 && < 5
-                     , cryptonite               >= 0.6
+                     , crypton                  >= 0.31
                      , cryptostore              >= 0.2
                      , memory                   >= 0.8
                      , bytestring               >= 0.10
@@ -47,8 +47,8 @@ library
                      , vector                   >= 0.7.1
                      , semigroups               >= 0.15.4
                      , network-uri
-                     , x509
-                     , x509-store
+                     , crypton-x509
+                     , crypton-x509-store
 
   hs-source-dirs:      src
   default-language:    Haskell2010
@@ -81,7 +81,7 @@ test-suite testsuite
                      , lens
                      , HUnit
                      , QuickCheck >= 2.4.0.1
-                     , cryptonite
+                     , crypton
                      , cryptostore
                      , memory
                      , bytestring               >= 0.10
@@ -95,8 +95,8 @@ test-suite testsuite
                      , vector                   >= 0.7.1
                      , semigroups               >= 0.15.4
                      , network-uri
-                     , x509
-                     , x509-store
+                     , crypton-x509
+                     , crypton-x509-store
 
   cpp-options: -DTEST