Made makefile changes for Travis CI to use pyflakes

[rambleraptor]

Added pyflakes install and pyflakes run for Travis CI and Makefile.

This should fix #268

[asottile]

Should really add pyflakes as a tox entry and add pyflakes to requirements-dev.txt

[asottile]

https://github.com/Yelp/yelp_encodings/blob/master/tox.ini#L14

[rambleraptor]

It seems like tox doesn't like quotes in commands. Any ideas how to fix this?

(the command is find testify -name 'init.py' -o -name '*.py' -print | xargs pyflakes)

[asottile]

@astephen2 Maybe just go for flake8, it'll be better longterm as well :) (and then you can noqa the stuff in __init__.py)

Most of the things it complains about seem pretty valid after applying this:

$ git diff
diff --git a/requirements-dev.txt b/requirements-dev.txt
index d59320c..cfc3bfa 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -1 +1,2 @@
 catbox
+flake8
diff --git a/tox.ini b/tox.ini
index 2f5e2b1..f97d7e5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,5 +2,10 @@
 envlist = py26,py27

 [testenv]
-commands = testify test -x fake -v --summary
+commands =
+    testify test -x fake -v --summary
+    flake8 testify tests testing_suite setup.py
 deps = -rrequirements-dev.txt
+
+[flake8]
+max-line-length = 131