Remove click dependency (only used in Flask demo - separate requirements)

Author: echarrod

requirements.in

@@ -1,5 +1,4 @@
 asn1==2.2.0
-click==7.0
 cryptography>=2.7.0
 cffi>=1.13.0
 future==0.15.2

requirements.txt

@@ -9,7 +9,6 @@ asn1crypto==0.24.0        # via cryptography
 certifi==2018.11.29       # via requests
 cffi==1.13.0              # via -r requirements.in, cryptography
 chardet==3.0.4            # via requests
-click==7.0                # via -r requirements.in
 cryptography==2.7         # via -r requirements.in, pyopenssl
 deprecated==1.2.6         # via -r requirements.in
 future==0.15.2            # via -r requirements.in