Local development errors on macOS with postgresql 10.0

[tnir]

Local development does not work on macOS with postgresql 10.0:

$ brew info postgresql | head -1
postgresql: stable 10.0 (bottled), HEAD
$ pip install -r requirements.txt
[...]
Collecting psycopg2==2.6.1 (from -r requirements.txt (line 4))
  Downloading psycopg2-2.6.1.tar.gz (371kB)
    100% |████████████████████████████████| 378kB 2.2MB/s
    Complete output from command python setup.py egg_info:
    running egg_info
    creating pip-egg-info/psycopg2.egg-info
    writing pip-egg-info/psycopg2.egg-info/PKG-INFO
    writing dependency_links to pip-egg-info/psycopg2.egg-info/dependency_links.txt
    writing top-level names to pip-egg-info/psycopg2.egg-info/top_level.txt
    writing manifest file 'pip-egg-info/psycopg2.egg-info/SOURCES.txt'
    warning: manifest_maker: standard file '-c' not found

    Error: could not determine PostgreSQL version from '10.0'

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/9_/k7p0mlkj41n03hf7kf85sXXXXXXXXX/T/pip-build-on90xxxx/psycopg2/

We should specify the latest version of psycopg2.