Investigate requirements.txt and requirements-dev.txt package specification

[jason-upchurch]

From openFEC README.md, running pip install -r requirements.txt generates the following warnings:

pgcli 2.1.0 has requirement psycopg2<2.8,>=2.7.4, but you'll have psycopg2 2.7.3.2 which is incompatible.
elasticsearch 5.5.1 has requirement urllib3<1.22,>=1.21.1, but you'll have urllib3 1.24.1 which is incompatible.
marshmallow-pagination 0.1.1 has requirement marshmallow-sqlalchemy==0.4.1, but you'll have marshmallow-sqlalchemy 0.15.0 which is incompatible.

And from openFEC README.md, running pip install -r requirements-dev.txt generates the following warnings:

pgcli 2.1.0 has requirement prompt-toolkit<2.1.0,>=2.0.6, but you'll have prompt-toolkit 1.0.15 which is incompatible.
pgcli 2.1.0 has requirement psycopg2<2.8,>=2.7.4, but you'll have psycopg2 2.7.3.2 which is incompatible.``

[jason-upchurch]

Issue no longer appears.