Added pycrypto dependency

Author: ddiazpinto

setup.py

@@ -9,7 +9,7 @@
 
 setup(
     name='redsys',
-    version='0.2.5',
+    version='0.2.6',
     packages=find_packages(),
     include_package_data=True,
     license='MIT License',
@@ -27,4 +27,5 @@
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
     ],
+    install_requires=['pycrypto>=2.6,<2.7']
 )