Inline dependency on smptapi.py (another SendGrid library)

It doesn't make much sense to pull in a single 60-line file as a full-on
dependency, especially when there's no other reason to be using it.

Test Plan:
Ran the following, all tests pass. The copying is for funky path stuff.

pip install unittest2
cp test/__init__.py test.py
python test.py

Auditors: desmond