Merge pull request loris-imageserver#493 from loris-imageserver/dependabot/pip/cryptography-2.3

Bump cryptography from 2.1.4 to 2.3

Author: alexwlchan

requirements.txt

@@ -10,7 +10,7 @@ certifi==2018.1.18        # via requests
 cffi==1.11.5              # via cryptography
 chardet==3.0.4            # via requests
 configobj==5.0.0
-cryptography==2.1.4
+cryptography==2.3
 idna==2.6                 # via cryptography, requests
 netaddr==0.7.19
 olefile==0.45.1           # via pillow

requirements_test.txt

@@ -11,7 +11,7 @@ cffi==1.11.5
 chardet==3.0.4
 configobj==5.0.0
 coverage==4.4.1
-cryptography==2.1.4
+cryptography==2.3
 flake8==3.5.0
 hypothesis==3.46.1
 idna==2.6