Fi server installation in Python 2.7 and 3.4

The jsonschema 3.2 requires pyrsistent>=0.14.0 [1]. The latest
version from pyrsistent is no longer compatible with Python 2.7
and Python 3.7. Because of this, explicit version from pyrsisten
is installed when jsonschema is needed on Python 2.7.

[1] https://github.com/Julian/jsonschema/blob/v3.2.0/setup.cfg

Signed-off-by: Heikki Laaksonen <laaksonen.heikki.j@gmail.com>

setup.py

@@ -39,6 +39,7 @@
     'jsonschema==3.2.0',
     'psycopg2==2.8.5 ; platform_python_implementation=="CPython"',
     'psycopg2cffi==2.8.1 ; platform_python_implementation=="PyPy"',
+    'pyrsistent==0.16 ; python_version=="2.7" or python_version=="3.4"',  # To get jsonschema to install in Python 2.7 and 3.4.
 )
 EXTRAS_DEV = (
     'colorama        ; python_version!="3.4"',  # To get openapi2jsonschema to install in Python 3.4.
@@ -54,8 +55,8 @@
     'sphinx-autobuild==0.7.1',
 )
 EXTRAS_RELEASE = (
-    'readme-renderer      ; python_version!="3.4"',  # To get twine to install in Python3.4.
-    'readme-renderer<25.0 ; python_version=="3.4"',  # To get twine to install in Python3.4.
+    'readme-renderer      ; python_version!="3.4"',  # To get twine to install in Python 3.4.
+    'readme-renderer<25.0 ; python_version=="3.4"',  # To get twine to install in Python 3.4.
     'setuptools',
     'twine       ; python_version!="3.4"',
     'twine<2.0.0 ; python_version=="3.4"',