SendGrid 1.4.3 broken in Python 3, introduce via `iteritems`

[urda]

Problem

sendgrid 1.4.3 is broken when used in a python3 context. A call is being made to iteritems during the set_headers call.

This iteritems call was introduced in commit afe99dc

Workaround

Python 3 users should not upgrade to 1.4.3 and remain at 1.4.2

Testing Environment

Bash Commands

# Environment setup
$ mkvirtualenv --python=/usr/bin/python3 sendgrid-issue

$ python --version
Python 3.4.3

# Upgrade pip, install sendgrid
$ pip install -U pip
$ pip install sendgrid
Collecting sendgrid
  Using cached sendgrid-1.4.3.tar.gz
Collecting smtpapi==0.2.0 (from sendgrid)
  Downloading smtpapi-0.2.0.tar.gz
Installing collected packages: smtpapi, sendgrid
  Running setup.py install for smtpapi
  Running setup.py install for sendgrid
Successfully installed sendgrid-1.4.3 smtpapi-0.2.0

# Confirm pip status
$ pip freeze
sendgrid==1.4.3
smtpapi==0.2.0

# Begin in next code section
$ python

Python sample

>>> import sendgrid
>>> message = sendgrid.Mail()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/purda/.virtualenvs/sendgrid-issue/lib/python3.4/site-packages/sendgrid/message.py", line 50, in __init__
    self.set_headers(opts.get('headers', {}))
  File "/home/purda/.virtualenvs/sendgrid-issue/lib/python3.4/site-packages/sendgrid/message.py", line 168, in set_headers
    for key, value in headers.iteritems():
AttributeError: 'dict' object has no attribute 'iteritems'

[thinkingserious]

This is fixed in this pull request: #128

Thanks!

[urda]

Aw yeah !