Update requirements.txt

remove broken versions

requirements.txt

@@ -2,19 +2,19 @@ alabaster==0.7.10
 Babel==2.3.4
 click==6.7
 docutils==0.13.1
-Flask==0.12
-Flask_API==1.0
+Flask
+Flask_API
 imagesize==0.7.1
 itsdangerous==0.24
-Jinja2==2.9.5
+Jinja2
 MarkupSafe==0.23
 pudb==2017.1.1
 py==1.4.32
-pycrypto==2.6.1
+pycrypto
 Pygments==2.2.0
 pytest==3.0.6
 pytz==2016.10
-requests==2.13.0
+requests
 six==1.10.0
 snowballstemmer==1.2.1
 Sphinx==1.7.1